StatGardenREF. DESK

Open the drawer, pick a tool

Every number you need, and the working underneath it.

Finance

Loans, savings, investing and everyday money maths. Every rate, term and price is an input you control, so nothing here is tied to a particular year’s figures.

Loan payment & amortisationRepayment on a fixed-rate amortised loan, with a year-by-year schedule.Mortgage repaymentFull monthly housing cost: principal, interest, rates, insurance and strata.Compound interestGrowth of a lump sum plus regular contributions.Simple interestInterest charged on the original principal only.Savings goalWhat you must put away each month to hit a target.Present & future valueWhat a future sum is worth today, and vice versa.Annuity / drawdown payoutHow much a pot pays out each month until it runs dry.Retirement projectionBalance at retirement and how long it lasts.Car loanRepayment after deposit, trade-in and on-road costs.Credit card payoffHow long a balance takes to clear at a fixed payment.APR to effective rate (APY)Converts a nominal rate into the true annual yield.Inflation & purchasing powerWhat money is worth after years of price rises.Return on investmentTotal and annualised return on an investment.CAGR (compound annual growth rate)The smooth yearly rate that links a start and end value.NPV & IRRDiscounted value of a project, and the rate that makes it break even.Rule of 72Quick mental estimate of doubling time.Salary & hourly rate converterMoves between hourly, weekly, monthly and annual pay.Tip & bill splitTip amount and what each person owes.Discount & sale pricePrice after one or two discounts, and what you save.Sales tax / GST / VATAdds tax to a net price, or strips it out of a gross one.Margin & markupTurns cost and price into margin, markup and profit.Break-even pointUnits and revenue needed before a business turns a profit.Debt-to-income ratioThe ratio lenders use to size your borrowing.How much can I borrowMaximum loan a given repayment supports.Bond price & yieldPresent value of a bond’s coupons and face value.Average share cost & positionBlended entry price across several buys.Currency conversion with feesWhat you actually receive after spread and fixed fees.Depreciation (straight-line & declining)Annual depreciation expense and remaining book value under two common methods.Payback periodHow many years of cash flows it takes to recover an initial investment, plain and discounted.Liquidity ratios (current, quick & cash)Three views of whether current assets can cover current liabilities.Leverage & solvency ratiosHow much of a company is financed by debt, and how easily it covers interest.Working capital & turnoverThe cash cushion between current assets and current liabilities, and how hard it is working.Cash conversion cycleDays between paying for inventory and collecting cash from its sale.WACC (weighted average cost of capital)The blended return a company must earn to satisfy both lenders and shareholders.CAPM (cost of equity)The return shareholders should require, given the market risk a stock carries.Dividend discount model (Gordon growth)Values a stock as its dividends, discounted and growing forever.Dividend yield & payout ratioWhat a stock pays relative to its price, and how much of earnings that consumes.EBITDA & marginOperating profitability before interest, tax, depreciation and amortisation.Enterprise valueThe theoretical takeover price of a company: equity plus debt, minus cash on hand.Stock valuation multiples (P/E, P/B, PEG)Common price ratios used to judge whether a stock is cheap or expensive.DuPont analysis (ROE breakdown)Splits return on equity into profitability, efficiency and leverage.Sharpe ratioReturn earned above the risk-free rate, per unit of volatility taken on.Perpetuity valuePresent value of a cash flow that continues forever, flat or growing.Balloon loan paymentRegular instalment on a loan amortised over a long schedule, plus the lump sum due early.Sustainable growth rateThe fastest a company can grow using only retained profit, no new borrowing or share issues.Graham numberBenjamin Graham’s quick estimate of a fair share price from earnings and book value.

Health

Body composition, energy needs, training load and cycle tracking, using the standard published clinical and sports-science formulas.

Body mass index (BMI)Weight relative to height, with the WHO category.BMR: basal metabolic rateEnergy burned at complete rest (Mifflin-St Jeor).TDEE: daily calorie needsBMR scaled by how active you are.Weight change timelineHow long a given calorie gap takes to shift a target.Body fat percentage (US Navy)Tape-measure estimate of body composition.Ideal body weightFour classic clinical formulas side by side.Macronutrient splitGrams of protein, carbs and fat for a calorie target.Daily water intakeBaseline fluid target adjusted for exercise and heat.Calories burned (MET)Energy cost of an activity from its metabolic equivalent.Heart rate training zonesKarvonen zones from resting and maximum heart rate.VO₂ max (Cooper test)Aerobic fitness from a 12-minute run.One-rep maxStrength ceiling estimated from a submaximal set.Running pace & finish timeConverts between pace, speed and race time.Pregnancy due dateEstimated delivery date from the last period (Naegele’s rule).Body surface areaUsed for drug dosing and cardiac index.Waist-to-hip & waist-to-heightFat distribution measures that track health risk.Ovulation & fertile windowLikely fertile days across a cycle.Sleep cycle timingWake times that fall between 90-minute sleep cycles.Anion gapUnmeasured ions in the blood, a first step in narrowing the cause of a metabolic acidosis.Corrected calcium for albuminAdjusts a total calcium reading for a low albumin level, using the Payne formula.Blood alcohol content (Widmark formula)Rough estimate of blood alcohol content from drinks consumed, body weight and time elapsed.Estimated average glucose from A1CConverts an HbA1c percentage into an average blood glucose reading, using the ADAG study formula.Corrected QT interval (QTc)Heart-rate-adjusted QT interval from an ECG reading, using the Bazett and Fridericia formulas.Creatinine clearance (Cockcroft-Gault)Estimated kidney filtration rate from age, weight and serum creatinine.Lean body mass (Boer formula)Fat-free body mass estimated from height and weight.Mean arterial pressure (MAP)Average pressure driving blood flow through the body over one heartbeat cycle.Total body water (Watson formula)Estimated volume of water in the body from age, height and weight.Fat-free mass index (FFMI)Muscularity measure that adjusts fat-free mass for height, comparable across body sizes.Smoking pack-yearsCumulative smoking exposure used in clinical risk screening.LDL cholesterol (Friedewald equation)Estimated LDL cholesterol from a standard lipid panel.Total cholesterol to HDL ratioA single number summarizing cardiovascular risk from a lipid panel.Daily protein intakeProtein target range based on body weight and activity level.Daily fiber intake targetRecommended dietary fiber based on total calorie intake.A Body Shape Index (ABSI)Waist circumference adjusted for height and BMI, an alternative to the waist-to-height ratio.Relative fat mass (RFM)Body fat percentage estimated from height and waist circumference (Woolcott-Bernstein formula).Shock indexHeart rate divided by systolic blood pressure, a quick marker of circulatory stress.Rate pressure productHeart rate times systolic blood pressure, an index of how hard the heart is working.HOMA-IR (insulin resistance)Estimated insulin resistance from fasting glucose and fasting insulin levels.

Maths

Percentages, fractions, algebra, number theory and trigonometry: the working shown alongside every answer.

PercentageThe three everyday percentage questions in one place.Percentage change & differenceIncrease, decrease and the symmetric difference.Fraction arithmeticAdd, subtract, multiply or divide two fractions and simplify.Decimal ↔ fractionClosest fraction to a decimal, at a chosen precision.GCD & LCMGreatest common divisor and lowest common multiple.Quadratic equationRoots, vertex and discriminant of ax² + bx + c.Ratio & proportionSolves a : b = c : d for the missing term.Exponents & rootsPowers, nth roots and scientific notation of the result.LogarithmLog in any base, plus the natural and common logs.Scientific notationConverts between plain numbers and a × 10ⁿ.Prime check & factorisationTests primality and lists the prime factors.Permutations & combinationsOrdered and unordered selections from a set.Number base converterBinary, octal, decimal, hex and any base to 36.Roman numeral converterArabic to Roman and back, 1 to 3999.Rounding & significant figuresRound to decimals, significant figures or a nearest step.Trigonometry: solve a triangleSine and cosine rules from two sides and the included angle.Trigonometric functionssin, cos, tan and their inverses for one angle.Modulo & integer divisionQuotient, remainder and the true mathematical modulo.Random number generatorDraws numbers from a range: press recalculate for a new set.Matrix determinant (2×2 or 3×3)Determinant of a 2×2 or 3×3 matrix from its entries.2×2 matrix inverseInverse of a 2×2 matrix using the adjugate formula.2×2 matrix operationsAdd, subtract or multiply two 2×2 matrices, and scale one by a constant.Vector dot productScalar dot product of two 3D vectors, and the angle between them.Vector cross productThe perpendicular vector from two 3D vectors, and the area of the parallelogram they span.Vector magnitude & unit vectorLength of a 3D vector and the unit vector pointing the same way.Arithmetic sequenceThe nth term and the sum of the first n terms of an arithmetic sequence.Geometric sequenceThe nth term and the sum of a geometric sequence, plus the infinite sum where it converges.Complex number arithmeticAdd, subtract, multiply or divide two complex numbers, plus modulus and argument.Synthetic divisionDivides a polynomial by (x − r) and returns the quotient and remainder.Equation of a lineSlope-intercept, point-slope and standard form of the line through two points.Distance & midpoint between two points (3D)Straight-line distance and midpoint between two points in 3D space (set z = 0 for 2D).Law of sines (solve a triangle)Finds the remaining sides and angles from two angles and one side.Arithmetic in standard formAdd, subtract, multiply or divide two numbers written as a × 10ⁿ.Binomial expansionExpands (x + y)ⁿ term by term using the binomial theorem.Distance from a point to a linePerpendicular distance from a point to a line given in general form.Geometric & harmonic meanTwo other kinds of average: the geometric mean and the harmonic mean of a list of positive numbers.Golden ratioSplits a length into golden-ratio proportions, or scales a rectangle side by φ.

Statistics

Averages, spread, distributions, confidence and correlation for data sets you paste straight in.

Descriptive statisticsMean, median, mode, spread and quartiles for a data set.Weighted averageAverage where each value carries its own weight.Z-score & percentileHow far a value sits from the mean, in standard deviations.Normal distribution probabilityArea under the bell curve between two points.Confidence interval for a meanMargin of error around a sample average.Required sample sizeHow many responses a survey needs.Correlation & linear regressionPearson r and the line of best fit for paired data.Binomial probabilityChance of exactly k successes in n independent trials.Probability of eventsCombines two event probabilities: and, or, neither.Odds ↔ probabilityConverts between fractional odds, decimal odds and percent.GPA / weighted gradeGrade point average across units with credit weights.Grade needed on the finalWhat the last assessment must score to hit a target.Coefficient of variationRelative variability of a data set: standard deviation as a percentage of the mean.SkewnessSample skewness: whether the data leans left or right of the mean (Excel-consistent adjusted formula).Poisson probabilityChance of a given number of independent events in a fixed interval, given the average rate.Geometric probabilityChance the first success happens on a given trial, for repeated independent trials.Hypergeometric probabilityChance of drawing an exact number of successes from a finite population, without replacement.Chi-square goodness of fitTests whether observed category counts match expected counts.Cohen's d (effect size)Standardised difference between two group means, in pooled standard deviations.Margin of error (proportion)Margin of error for a survey proportion at a chosen confidence level.Relative riskCompares event risk between an exposed and an unexposed (or treated and control) group.T-statistic (one or two sample)How many standard errors a sample mean, or the gap between two means, is from the reference value.Z-test for a proportionTests a sample proportion against a hypothesised population proportion.Expected value of a discrete distributionMean and standard deviation of a discrete random variable from its outcomes and probabilities.Outlier fences (Tukey)The IQR-based cutoffs beyond which a data point counts as an outlier.

Geometry

Area, perimeter, volume and surface area for flat shapes and solids, plus coordinate geometry.

CircleArea, circumference and diameter from any one measure.Circle sector & arcA wedge of a circle: arc length, area and chord.Triangle from three sidesArea, angles and centres via Heron’s formula.Right triangle / PythagorasThird side, angles and area of a right-angled triangle.Rectangle & squareArea, perimeter and diagonal.TrapezoidArea and perimeter of a four-sided figure with parallel sides.Parallelogram & rhombusArea from base and height, or from sides and angle.EllipseArea, perimeter (Ramanujan) and eccentricity.Regular polygonArea, angles and radii of an n-sided regular shape.SphereVolume and surface area from the radius.CylinderVolume, surface area and capacity of a tube or tank.ConeVolume, slant height and surface area.Rectangular prism & cubeVolume, surface area and space diagonal of a box.PyramidVolume and surface area of a rectangular-based pyramid.Torus (ring)Volume and surface of a doughnut shape.Distance, midpoint & slopeEverything about the line between two points.Area & volume unit scalingHow area and volume change when a shape is scaled.

Conversion

Unit converters that show the full ladder of equivalents at once, not just the one pair you asked for.

Length & distanceMetric and imperial length, from millimetres to nautical miles.Weight & massGrams, kilograms, pounds, ounces, stone and tonnes.Volume & capacityLitres, millilitres, gallons, pints, cups and cubic units.AreaSquare metres, hectares, acres and square feet.SpeedKilometres per hour, miles per hour, metres per second, knots.TimeSeconds through to centuries.Digital storageBytes, kilobytes, mebibytes and the binary versus decimal split.PressurePascals, bar, psi, atmospheres and millimetres of mercury.EnergyJoules, calories, kilowatt-hours and BTU.PowerWatts, kilowatts, horsepower and BTU per hour.AngleDegrees, radians, gradians and turns.Cooking measuresCups, spoons, millilitres and fluid ounces for the kitchen.TemperatureCelsius, Fahrenheit, Kelvin and Rankine.Fuel economyLitres per 100 km, miles per gallon and km per litre.Height & weight (imperial ↔ metric)Feet-and-inches and stone-and-pounds, both ways.TorqueNewton-metres, foot-pounds, inch-pounds and kilogram-force metres.Paper quantitySheets, quires and reams, the units the printing and stationery trade uses.Concentration (ppm, ppb, %)Parts per million, parts per billion and percentage, as the same ratio expressed differently.12-hour ↔ 24-hour (military) timeClock time converted to 24-hour military format, and back.

Date & time

Ages, durations, working days, deadlines and timesheets, calculated on real calendar arithmetic.

Age calculatorExact age in years, months and days, plus the next birthday.Days between datesElapsed time between two dates, with and without weekends.Add or subtract from a dateThe date a set number of days, weeks or months away.Working daysCounts weekdays between two dates, less any holidays.Time duration arithmeticAdds and subtracts hours, minutes and seconds.Timesheet & payHours worked in a shift and what they are worth.Day of the week & week numberWhich weekday a date falls on, plus ISO week and day of year.Countdown to a dateTime remaining until a deadline or event.Unix timestamp converterEpoch seconds to a readable date and back.

Physics

Mechanics, electricity, energy and waves: first-principles formulas with every constant stated.

Ohm’s lawVoltage, current, resistance and power from any two.Resistors in series & parallelCombined resistance of up to four resistors.Voltage dividerOutput voltage across the lower resistor of a pair.Electricity running costWhat an appliance costs to run over time.Force, mass & accelerationNewton’s second law, with weight under gravity.Kinetic & potential energyEnergy of a moving or raised mass.Speed, distance & timeJourney arithmetic in metric and imperial.Acceleration & stopping distanceUniform acceleration, braking distance and reaction gap.Projectile motionRange, peak height and flight time of a launched object.Density, mass & volumeAny one of the three from the other two.Pressure from force or depthPressure under a load, and water pressure at depth.Wave speed, frequency & wavelengthRelates the three properties of any wave.Work, power & efficiencyEnergy transferred, the rate of transfer and what is lost.Momentum & impulseMomentum of a mass and the force needed to change it.Ideal gas lawPressure, volume, temperature and moles of a gas.Torque & rotational powerTurning force, and the power it delivers at a given speed.Centripetal force & circular motionForce, acceleration and period of an object moving in a circle at constant speed.Hooke's law & spring energyRestoring force and stored energy of a stretched or compressed spring.Pendulum periodSwing period of a simple pendulum for small angles.Elastic & inelastic collisionFinal velocities of two colliding masses, in a straight line.Capacitor charge & energyStored charge and energy of a capacitor at a given voltage.Inductor stored energyMagnetic energy stored in an inductor carrying current.RC circuit charge & dischargeHow a capacitor charges or discharges through a resistor over time.Carnot efficiencyMaximum possible efficiency of a heat engine between two temperatures.Linear thermal expansionHow much a material lengthens or shortens with a temperature change.Heat energy & specific heatHeat needed to change the temperature of a mass of material.Snell's law of refractionAngle of refraction as light passes between two media.Thin lens equationImage distance and magnification for a lens of known focal length.Doppler effect (sound)Observed frequency of a sound source moving relative to a listener.Sound intensity level (decibels)Decibel level of a sound from its intensity, referenced to the hearing threshold.Escape velocityMinimum speed to escape a body’s gravity from a given distance, ignoring drag.Circular orbital velocitySpeed and period needed to hold a circular orbit around a mass.Kepler's third lawOrbital period of a body from its orbit size and the mass it orbits.Buoyancy (Archimedes’ principle)Upward force on an object from the fluid it displaces, and whether it floats.Terminal velocityMaximum falling speed once drag balances gravity.Angular momentum (point mass)Rotational momentum of a point mass moving on a circular path.

Home & build

Quantities and sizing for renovation, landscaping and trade work: paint, tiles, concrete, roofing and more.

Paint requiredLitres of paint for walls, allowing for doors and windows.Flooring & tilesBoxes of tiles or boards needed, including wastage.Concrete volumeCubic metres for a slab, footing or set of posts.Mulch, soil & gravelBulk material for a garden bed at a given depth.Roof pitch & rafter lengthAngle, slope factor and true roof area.Fencing & decking materialsPosts, rails and boards for a run of fence or deck.Air conditioner sizingCooling capacity for a room, adjusted for sun and occupancy.Tank & pool volumeCapacity of a rectangular or round tank in litres.Drywall sheets neededPlasterboard sheets for a room, allowing for openings and waste.Bricks or blocks neededMasonry units for a wall, from unit size and mortar joint thickness.Stair rise & runStep count, riser height and comfort check for a straight staircase.Pavers & bedding sandNumber of pavers and bedding sand volume for a patio or path.Roof shingle bundlesBundles of shingles needed, accounting for slope and waste.Board feet of lumberBoard feet and cost for a batch of dimensional lumber.Baluster / spindle spacingEven spindle count and gap for a stair or deck railing.Wallpaper rolls neededRolls required for a room, accounting for pattern repeat.Wall stud countStuds needed for a wall on a chosen centre spacing, plus openings.Ladder angle & base distanceSafe base distance and length for a leaning ladder, using the 4-to-1 rule.Insulation thickness & coverageThickness needed to hit a target R-value, and rolls required for an area.

Everyday

Practical comparisons for shopping, travel, cooking and time: the small calculations that add up.

Trip fuel costFuel and time for a journey, split between passengers.Unit price comparisonWhich pack is actually cheaper per unit.Recipe scalerRescales quantities and adjusts baking time.Aspect ratio & screen sizeResize while keeping proportions, or find screen dimensions.Pizza & round-item valueArea per dollar: the honest way to compare sizes.Reading & speaking timeHow long a word count takes to read aloud or silently.Password strengthEntropy in bits and how long a brute force would take.Coffee brew ratioGrounds and water for a chosen strength.Hours of work to buy somethingPrices a purchase in hours of your life.Battery charge timeHow long a device takes to charge from its current level to a target level.Typing speed (WPM)Gross and net words per minute, and accuracy, from a timed typing sample.Luggage linear inchesChecks a bag against an airline’s combined length + width + height limit.Cost of a meetingWhat a meeting actually costs in attendee salary time.True cost per mile to driveAll-in running cost of a vehicle, spread across the miles driven.Weight of a pile of cashHow much a dollar amount weighs in bills or coins.2-stroke fuel mix ratioOil to add to a volume of petrol for a chosen mix ratio.Generator sizingGenerator capacity needed to cover a set of appliances, including starting surge.LED bulb savingsElectricity and replacement-bulb savings from switching to LED lighting.Event tables & seatingTables needed for a guest count, for round or rectangular tables.Pomodoro session plannerHow many focused work intervals a task will take, breaks included.Money saved by quitting smokingWhat not buying cigarettes adds up to over time.Roll length remainingHow much material is left on a roll, from its diameter and material thickness.Cost of a showerWater and water-heating energy cost for one shower.EV home charging cost & timeCost and time to charge an electric vehicle from one charge level to another.Binge-watch time plannerTotal time to finish a TV series, and how many days that takes.Moon phase finderThe approximate Moon phase on any date, from the lunar synodic cycle.Weighted blanket sizeRecommended blanket weight from body weight, using the common 10% rule.Mobile data usageDaily and monthly data use from your mix of everyday activities, and how long a data cap will last.

Growth

Growth rates for revenue, users and any other metric that moves period to period: YoY, MoM, QoQ and beyond, each with its own dedicated page.

Year-over-year (YoY) growthGrowth between this period and the same period a year ago.Month-over-month (MoM) growthGrowth between this month and last month, with the annualised equivalent.Quarter-over-quarter (QoQ) growthGrowth between this quarter and the previous quarter, with the annualised equivalent.Week-over-week (WoW) growthGrowth between this week and last week, with the annualised equivalent.Day-over-day (DoD) growthGrowth between today and yesterday, with the annualised equivalent.Period-over-period (PoP) growthGrowth between any two comparable periods you define, with a custom annualising cadence.Compound monthly growth rate (CMGR)The smooth monthly rate that links a start and end value over several months.Annualised run rateExtrapolates a single period of revenue to a full-year figure.Rule of 40Checks whether growth rate plus profit margin clears the 40% SaaS health benchmark.User & customer growth rateNet growth rate for a user base once new signups and churned users are both counted.Revenue growth & target plannerGrowth achieved between two periods, and the revenue needed next period to hit a target rate.

Chemistry

Concentrations, pH, dilutions and reaction yields: the maths behind the lab bench.

Molarity from massConcentration of a solution made from a known mass of solute.Solution dilution (C₁V₁ = C₂V₂)Stock volume and diluent needed to hit a target concentration.pH from hydrogen ion concentrationConversion between [H⁺] and pH, with pOH and [OH⁻] at 25 °C.Henderson–Hasselbalch (buffer pH)Buffer pH from the acid dissociation constant and the base/acid ratio.Percent yieldHow much product a reaction actually gave versus the theoretical maximum.Mass percent concentrationSolute mass as a percentage of total solution mass, plus ppm.Radioactive decay & half-lifeAmount of a substance remaining after a given elapsed time.Beer–Lambert law (absorbance)Absorbance and transmittance of a solution from its concentration.Osmotic pressure (van’t Hoff)Pressure needed to stop osmosis across a semipermeable membrane.

Biology

Population genetics, enzyme kinetics, growth curves and lab concentration formulas.

Hardy–Weinberg equilibriumExpected genotype frequencies in a non-evolving population from allele frequency.DNA/RNA concentration from A₂₆₀Nucleic acid concentration from a spectrophotometer absorbance reading.Log reduction (microbial kill)How many orders of magnitude a treatment reduces a microbial count.Michaelis–Menten kineticsEnzyme reaction rate at a given substrate concentration.Bacterial/cell growth (doubling time)Population size after exponential growth at a fixed doubling time.Q₁₀ temperature coefficientHow much a biological or chemical rate changes per 10 °C rise.Plant water potentialTotal water potential from solute and pressure potential in a plant cell.

Ecology

Population and diversity formulas for the field: carrying capacity, species diversity and predator-prey dynamics.

Logistic population growthPopulation size over time under a fixed carrying capacity (Verhulst model).Shannon diversity indexBiodiversity of a community from species counts.Lotka–Volterra predator–prey ratesInstantaneous population growth rates for a classic predator–prey pair.Kaya identity (CO₂ emissions)Global CO₂ emissions decomposed into population, wealth, energy and carbon factors.

Sports

Performance and scoring maths for training and competition, from gear ratios to rating systems.

Bike gear ratio & speedGear ratio, development and road speed for a given chainring, cog and cadence.Bike frame sizeRecommended frame size from inseam length, by bike type.Stride length & distance from stepsStride length from height, and a step count turned into distance.Hull speed (displacement boat)The theoretical top speed of a displacement-hull boat from its waterline length.Wilks score (powerlifting)Bodyweight-adjusted strength score for comparing lifters across weight classes.Elo rating changeHow a single result moves a player or team’s Elo rating.NFL passer ratingThe 0–158.3 quarterback rating from completions, yards, touchdowns and interceptions.Race time predictorPredicts a finish time at a new distance from a recent race result, using Riegel’s formula.Hiking time (Naismith’s rule)Estimated walking time for a hike from distance and total ascent.Bruce protocol VO₂maxEstimated maximal oxygen uptake from total time on a standard Bruce treadmill test.Magic number (pennant race)Combined wins by your team and losses by the nearest rival needed to clinch a spot.Net run rate (cricket)The run-rate differential used to separate teams level on points.

Food

Kitchen and brewing ratios: baker’s percentages, dilutions, yields and the maths behind a recipe that scales.

Baker’s percentage & hydrationExpresses every dough ingredient as a percentage of the flour weight, the way bakers formulate recipes.Brine strengthSalt needed to make a brine of a given strength, by weight of the water.ABV from gravity readingsAlcohol by volume of a home-brewed beer or wine from hydrometer readings.Alcohol dilutionWater needed to cut a spirit down from one ABV to a weaker target ABV.Yeast type converterA quantity of yeast converted between active dry, instant and fresh (cake) forms.Self-rising flour from all-purposeBaking powder and salt to turn plain flour into self-rising flour.Rice to water ratioWater needed to cook a given amount of rice, and the approximate cooked yield, by rice type.Dry to cooked pasta weightHow much a portion of dry pasta weighs once boiled, given its typical expansion factor.Party drink plannerTotal drinks needed for a party, split across beer, wine and spirits.Cake servingsHow many servings a round or rectangular cake yields at a given slice size.Ice cream overrunHow much the volume of a churned ice cream mix has grown from the air whipped into it.

Pets

Sizing, feeding and age-conversion maths for the animals in your household, from crate size to daily calories.

Dog age in human yearsA dog's age converted to a human-equivalent age using the epigenetic-clock formula.Cat age in human yearsA cat's age converted to an equivalent human age using the standard veterinary chart.Pet gestation & due dateExpected birth date range for a common pet or farm animal, from the breeding date.Dog & cat daily caloriesDaily energy needs from resting energy requirement and an activity factor.Dog daily water intakeRoughly how much water a dog needs per day, by activity level.Dog crate sizeMinimum crate dimensions so a dog can stand, turn around and lie stretched out.Turtle tank sizeMinimum water volume for a pet turtle based on shell length.Chicken coop & run sizeMinimum floor space for a flock, depending on how much outdoor access they get.Dog chocolate toxicity riskTheobromine dose from chocolate eaten, checked against published toxicity thresholds.Rabbit cage sizeMinimum enclosure dimensions based on a measured hop, body length and standing height.Dog daily food amountDaily feeding amount as a percentage of body weight, by life stage.Cost of owning a petFirst-year and ongoing costs from your own monthly and one-off figures.