What this calculator does
Not every comparison fits neatly into a day, week, month or quarter. A four-week marketing sprint, a six-week product cycle, a biennial trade show: any pair of comparable periods can be measured the same way, as long as the cadence between them is stated so the growth rate can be put on a common annual footing.
This calculator is the general-purpose version of the fixed-cadence growth calculators in this category: instead of assuming the period is a day, week, month or quarter, you tell it directly how many of these periods make up a year, and it annualises accordingly.
The formula
The period-over-period rate is the plain percentage change between the two periods, exactly as in every other calculator in this category. What differs is the annualising step: rather than a fixed exponent of 12, 4, 52 or 365, this calculator raises (1 + PoP) to the power of however many periods per year you specify, so a five-week cycle annualises over 10.4 periods and a six-week cycle over about 8.7.
| Term | Meaning |
|---|---|
| This period | The current period’s figure. |
| Last period | The immediately preceding, equal-length period’s figure. |
| Periods per year | How many of these periods make up a full year: 12 for monthly, 4 for quarterly, 26 for fortnightly, and so on for anything in between. |
| PoP growth | (This period − last period) ÷ last period × 100. |
The inputs explained
| Field | What to enter |
|---|---|
| This period’s value | The current period’s figure. |
| Last period’s value | The immediately preceding, equal-length period’s figure. |
| Periods per year | How many of these periods occur in a year. A fortnightly cycle is 26, a four-week cycle is 13, a six-week cycle is about 8.7. |
When to use it
Measuring a marketing sprint or campaign cycle
A four-week campaign cadence does not map onto “month” or “quarter” cleanly. Entering 13 as the periods-per-year figure annualises it correctly rather than forcing it into a monthly box that overstates or understates the true rate.
Comparing a biennial or triennial event
Trade shows, conferences and some capital projects recur on cycles longer than a year. A periods-per-year figure below 1 (such as 0.5 for a biennial event) still works in the same formula.
Standardising an irregular reporting cadence
Some businesses report on 4-4-5 week fiscal periods rather than calendar months. This calculator lets that exact cadence be entered directly instead of approximating it as a standard month.
Comparing growth rates measured on different cadences
Annualising is what makes a fortnightly growth rate and a quarterly growth rate comparable on the same footing: the raw period-over-period percentages alone cannot be compared directly.
Worked examples
Every figure in the tables below is produced by this page’s own calculator at build time, so the numbers and the tool always agree. Select any row to load that scenario.
The same period-over-period rate annualised at different cadences
A fixed 3% gain from 5,000 to 5,150, annualised as if it recurred at various cadences.
| Periods per year | PoP growth | If sustained, annualised rate |
|---|---|---|
| 1 | 3.00% | 3.00% |
| 4 | 3.00% | 12.6% |
| 12 | 3.00% | 42.6% |
| 26 | 3.00% | 115.7% |
| 52 | 3.00% | 365.1% |
| 365 | 3.00% | 4,848,172.5% |
How the growth rate shifts against a fixed current figure
A monthly cadence (12 periods a year) with the current period held at 5,150 while the prior period varies.
| Last period | PoP growth | Change | If sustained, annualised rate |
|---|---|---|---|
| 4,000 | 28.7% | 1,150.00 | 1,974.8% |
| 4,500 | 14.4% | 650.000 | 404.8% |
| 5,000 | 3.00% | 150.000 | 42.6% |
| 5,150 | 0.000% | 0 | 0.000% |
| 5,500 | -6.36% | -350.000 | -54.6% |
| 6,000 | -14.2% | -850.000 | -84.0% |
Questions
How do I work out the periods-per-year figure for an unusual cycle?
Divide 365 by the number of days in the period (for a 28-day cycle, 365 ÷ 28 ≈ 13.04), or 52 by the number of weeks. The figure does not need to be a whole number.
Can periods per year be less than 1?
Yes: for a period longer than a year, such as a biennial event, use a fraction like 0.5. The same formula still applies; the outcome simply reflects a rate compounded less than once a year.
How is this different from the fixed-cadence calculators in this category?
The month-over-month, quarter-over-quarter, week-over-week and day-over-day calculators are this same formula with the periods-per-year figure fixed at 12, 4, 52 and 365 respectively. This one is for anything that does not fit those four cadences.
Does the periods-per-year input affect the PoP growth figure itself?
No: it only affects the annualised figure. The plain period-over-period growth rate depends only on the current and prior period values, exactly as in the other calculators here.
Why does the annualised rate change so much with the cadence?
Because it reflects how many times a year the same percentage gain would compound. A rate that compounds 52 times a year grows far faster than the same rate compounding only 4 times, even though the underlying per-period rate is identical.
For the standard monthly cadence, see the month-over-month growth calculator. For a smoothed multi-year rate instead of a single short period, use the compound monthly growth rate calculator.