How the Year Over Year Growth Calculator works
Year-over-year (YoY) growth measures how much a figure changed compared with the same period one year earlier (or, more generally, n years earlier). It is the standard way to compare revenue, users, sales, or any recurring metric while canceling out normal seasonal swings — comparing December to November tells you less than comparing this December to last December.
The formula
For a prior-period value P and a current-period value C, year-over-year growth is:
YoY growth (%) = (C − P) / P × 100
When the two values are more than one year apart, the calculator also reports the compound annual growth rate (CAGR), which spreads the total change evenly across each year in between:
CAGR (%) = ((C / P)1/n − 1) × 100
where n is the number of years between the two values. When n = 1, CAGR and YoY growth are the same number.
Worked example
Say prior-year revenue was $850,000 and this year's revenue is $972,000. The absolute change is $122,000, and YoY growth is $122,000 / $850,000 × 100 ≈ 14.35%. If instead those two values were three years apart, the CAGR would be (972,000 / 850,000)1/3 − 1 ≈ 4.57% per year — a lower figure because it spreads the same total gain over three years instead of crediting it all to one.
Getting accurate results
- Compare like periods — a full year to a full year, or the same month/quarter to the same month/quarter last year. Mixing partial and full periods distorts the percentage.
- Enter the prior-period (older) value first and the current-period (newer) value second; reversing them flips the sign of the result.
- The prior-period value cannot be zero, since it is the denominator in the growth formula — division by zero is undefined.
- Only set "years between periods" above 1 when you are deliberately comparing values that are more than a year apart (for example, this year versus three years ago).
Interpreting the output
A positive percentage means the metric grew; a negative percentage means it shrank. The size of the swing matters as much as the sign — a metric that is naturally volatile (a small startup's monthly signups, for instance) can show large percentage swings from a small base, while a large, stable base tends to move more slowly in percentage terms even when the dollar change is sizable. Use the CAGR figure, not the raw YoY percentage, when you are annualizing a multi-year change so you don't overstate how fast growth is actually compounding per year.
Next steps
- Record the exact prior and current values alongside the result so the calculation can be reproduced later.
- Compare the YoY figure against your own trailing average to see whether this period is accelerating or decelerating relative to trend.
- Re-run the calculation each time a new period closes so the growth trend stays current.