What this calculator does
Year-over-year growth compares a figure to the same point twelve months earlier, which cancels out any seasonal pattern within the year. Retail revenue in December always beats November, so a month-over-month comparison there is meaningless; comparing this December to last December is not.
The calculation itself is the simplest one in this category: the change divided by the starting value. What YoY adds is discipline about which two numbers to compare, so seasonal swings are not mistaken for real growth or real decline.
The formula
Subtract last year’s value from this year’s to get the change, then divide by last year’s value to get the rate. A multiplier is the same information in another shape: 1.20× means this year is 20% larger than last year, and 0.75× means it has shrunk to three-quarters of its former size.
| Term | Meaning |
|---|---|
| This year | The current period’s figure. |
| Same period last year | The figure from exactly twelve months earlier, for a like-for-like comparison. |
| YoY growth | (This year − last year) ÷ last year × 100. |
| Multiplier | This year’s value as a multiple of last year’s, equal to 1 + the growth rate. |
The inputs explained
| Field | What to enter |
|---|---|
| This year’s value | The figure for the current period. |
| Same period last year | The figure from the same period twelve months ago, not last month. |
When to use it
Reporting revenue or user growth
YoY is the standard figure in earnings reports and board decks precisely because it strips out seasonality, letting a reader compare Q4 to Q4 rather than Q4 to a quieter Q3.
Judging a business with a strong seasonal pattern
A ski resort or a beach cafe has wild month-to-month swings that mean nothing. Whether this July beat last July is the number that actually says something about the trend.
Checking a headline growth claim
A company announcing “40% growth” without saying over what period could mean almost anything. Recomputing it as YoY from the underlying figures puts it on a comparable footing with everyone else’s YoY numbers.
Spotting a slowdown before it shows up elsewhere
A string of YoY figures that are still positive but shrinking each quarter is an early signal of deceleration, well before growth actually turns negative.
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.
How the YoY figure changes as this year’s result varies
A fixed prior-year figure of 110,000 against a range of outcomes for this year.
| This year | YoY growth | Change | Multiplier |
|---|---|---|---|
| 99,000 | -10.0% | -11,000.00 | 0.900× |
| 110,000 | 0.000% | 0 | 1.000× |
| 121,000 | 10.0% | 11,000.00 | 1.100× |
| 132,000 | 20.0% | 22,000.00 | 1.200× |
| 154,000 | 40.0% | 44,000.00 | 1.400× |
| 176,000 | 60.0% | 66,000.00 | 1.600× |
How the same current figure reads against different starting points
The current figure held at 132,000 while the comparison base from a year ago shifts.
| Same period last year | YoY growth | Change | Multiplier |
|---|---|---|---|
| 88,000 | 50.0% | 44,000.00 | 1.500× |
| 110,000 | 20.0% | 22,000.00 | 1.200× |
| 120,000 | 10.0% | 12,000.00 | 1.100× |
| 132,000 | 0.000% | 0 | 1.000× |
| 150,000 | -12.0% | -18,000.00 | 0.880× |
| 176,000 | -25.0% | -44,000.00 | 0.750× |
Questions
Why use YoY instead of comparing to last month?
Because most real-world metrics have a seasonal pattern within the year. Comparing to the same month last year removes that pattern, so what is left reflects underlying growth or decline rather than the time of year.
Can YoY growth be negative?
Yes: a negative figure means the current period is smaller than the same period a year ago. The multiplier falls below 1× in that case, for example 0.88× for a 12% decline.
What counts as “the same period” if my year doesn’t start in January?
Any consistent twelve-month offset works: fiscal quarters, trailing twelve months, or a specific month. What matters is comparing genuinely equivalent points, not that the calendar starts on 1 January.
Is a multiplier of exactly 1.00× the same as 0% growth?
Yes, they are the same thing stated two ways. A multiplier of 1.00× means the current figure exactly equals last year’s, with no growth or decline.
How is YoY different from CAGR?
YoY compares exactly two points a year apart. CAGR (compound annual growth rate) smooths a longer run of years into a single average annual rate. For a single one-year comparison the two give the same number; over multiple years they diverge.
For a shorter, more volatile comparison window, see the month-over-month growth calculator. For a smoothed multi-year rate, use the CAGR calculator.