Percentage Change Calculator
Calculate the percentage increase or decrease between two values.
Increase of 20%
About this tool
Percentage change measures how much a value has grown or shrunk relative to its starting point. It's one of the most widely used calculations in finance, business and everyday life — used to describe price changes, salary raises, population growth, stock performance, and year-over-year comparisons.
Unlike a simple difference (which just tells you the absolute gap between two numbers), percentage change tells you how significant that gap is relative to where you started. A $10 increase means very different things depending on whether the starting price was $20 or $2,000 — percentage change captures that difference.
This calculator automatically detects whether the change is an increase or a decrease and labels the result accordingly, so you don't need to interpret a negative sign.
Worked example
- 1Enter the old (starting) value and the new (ending) value.
- 2Subtract the old value from the new value to get the raw change. Example: from 80 to 100 → change of 20.
- 3Divide that change by the old value and multiply by 100: (20 / 80) × 100 = 25% increase.
Formula
Percentage change = ((New value − Old value) / |Old value|) x 100
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Frequently asked questions
- How do I calculate percentage increase?
- Subtract the old value from the new value, divide by the old value, then multiply by 100. If the result is positive, the value increased; if negative, it decreased.
- What does a negative percentage change mean?
- A negative result means the value decreased. The calculator shows this as a percentage decrease rather than a negative increase, which is easier to read.
- Why divide by the old value and not the new value?
- Percentage change is always measured relative to the starting point, because that's the baseline you're comparing against. Dividing by the new value instead would answer a different question (how big the old value was relative to the new one).
- What's the difference between percentage change and percentage points?
- Percentage change is a relative measure (e.g. sales went up 20% from last year), while a percentage point difference is an absolute measure between two percentages (e.g. an interest rate rising from 5% to 7% is a 2 percentage point increase, but a 40% relative increase).