A rate of change measures how fast a value is changing, relative to another variable — almost always time. It's a percentage change with a time dimension attached: not just "how much did it change," but "how much did it change per day, per month, or per year."
Rate of change (%) = Percentage change ÷ number of time periods
This is a simplified, average rate — for the more precise way of finding an average annual rate over multiple compounding periods, see the CAGR calculator.
A simple example
A company's revenue grows from $200,000 to $242,000 over 2 years. What is the percentage change, and what is the rate of change per year?
Percentage change: (242000 − 200000) / 200000 × 100 = 21%
Rate of change: 21% ÷ 2 years ≈ 10.5% per year (a simple average, not compounded)
Note that this simple average differs slightly from the true compounded annual rate (CAGR), which accounts for growth building on itself each year. For year-over-year figures specifically, see the year-over-year guide.
Rate of change in different fields
- Business: revenue growth rate, customer churn rate
- Science: reaction rates, population growth rate
- Finance: interest accrual, inflation rate
- Everyday life: speed (distance changing over time), fuel consumption
Frequently asked questions
Is rate of change the same as percentage change?
Not quite. Percentage change is a single number describing the total change between two points. Rate of change expresses that change relative to a time period, letting you compare changes that happened over different lengths of time.
Should I use a simple average or CAGR?
A simple average (as shown above) is easier to calculate and fine for a quick estimate. CAGR is more accurate over multiple periods because it accounts for compounding — see the daily vs monthly guide for why compounding matters.
Ready to calculate your own numbers? Use the percentage change calculator, or find a compounded annual rate with the CAGR calculator.