Percentage Increase / Decrease
Two directions in one tool: find the % change between two numbers, or apply a % change to a starting number.
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How to calculate a percentage increase or decrease
- Choose Find % change between two numbers, or Apply a % change to a number.
- To find a change, type the old value in From and the new value in To.
- To apply a change, type the starting number, the percentage and whether it’s an increase or decrease. The result updates as you type.
The formulas
% change = ((new − old) ÷ old) × 100 — a positive result is an increase, negative is a decrease.
new value = old × (1 ± percentage ÷ 100) — add for an increase, subtract for a decrease.
Questions about percentage change
How do I calculate a percentage increase?
Subtract the old value from the new one, divide by the old value and multiply by 100. From 50 to 65: (65 − 50) ÷ 50 × 100 = 30% increase.
How do I calculate a percentage decrease?
Use the same formula; the answer comes out negative. From 80 to 60: (60 − 80) ÷ 80 × 100 = −25%, a 25% decrease.
Why doesn’t a 50% rise followed by a 50% fall get back to where I started?
Because the second percentage is of a different number. 100 up 50% is 150, and 150 down 50% is 75. To undo a 50% rise you need a 33.3% fall.
What is the difference between percentage change and percentage points?
If an interest rate goes from 2% to 3%, that’s a rise of 1 percentage point, but a 50% increase in the rate itself.