Percent change calculator
Find the percent increase or decrease between two numbers, apply a percent change to a number, or work backwards to the original value. The working is shown under the answer.
Worked example
With the values shown above when the page opens:
A 25% increase
- Percent change = (B − A) ÷ A × 100
- = (100 − 80) ÷ 80 × 100
- = 20 ÷ 80 × 100
- = 25%
How it works
- Percent change = (new − old) ÷ old × 100. A positive answer is an increase, a negative one a decrease.
- To apply a change, multiply by (1 + P/100) for an increase or (1 − P/100) for a decrease.
- To undo a change, divide by the same factor. A 20% increase is undone by dividing by 1.2, not by taking 20% off.
Questions
Why does a 50% increase followed by a 50% decrease not get back to the start?
The second change is taken from a bigger number. 100 up 50% is 150, and 150 down 50% is 75, which is a 25% fall overall.
How do I calculate the original price before a discount?
Choose the "original value, after a decrease" option. If a jacket costs 60 after a 25% discount, the original was 60 ÷ 0.75 = 80.
Is percent change the same as percentage points?
No. Going from 40% to 50% is 10 percentage points, but a 25% increase.
Related
Calculators are for learning and quick checks. Check important figures yourself, and do not rely on them for tax, legal or financial decisions.