Formula
% change = (new − start) ÷ |start| × 100
- start — the starting (old) value, must not be zero
- new — the value after the change
Positive means it went up, negative means it went down, zero means it did not change.
Worked examples
From 60 to 50
- Starting value
- 60
- New value
- 50
Percentage change
−16.6667%
Direction: Decrease
Absolute change: −10
Ratio (new ÷ old): 0.833333
From 50 to 60
- Starting value
- 50
- New value
- 60
Percentage change
20%
Direction: Increase
Absolute change: 10
Ratio (new ÷ old): 1.2
How it works
Percentage change always has a direction and a starting point. From 60 to 50 the value changed by −10, and −10 ÷ 60 × 100 = −16.67%. Reverse the numbers and you get +20%, because the starting point is different.
Use this tool when one value clearly came first — a price, a score, a population. When neither value is the baseline (two stores' prices, two measurements of the same thing) use Percentage Difference Calculator, which treats both values equally.
The tool also reports the absolute change and the ratio of new to old. If you only want increases or decreases presented as positive numbers see Percentage Increase Calculator and Percentage Decrease Calculator.
Assumptions and limits
- A starting value of zero is rejected: a percentage change from nothing is undefined.
- If the starting value is negative the change is measured against its size, so a move from −50 to −25 shows as +50%.