Percentage Calculator
Five everyday percentage calculations in one place. Each one shows the answer, the formula with your numbers, and what the result means.
All calculations happen in your browser.
What is X% of Y?
20% of 150 = 30
20 ÷ 100 × 150 = 30
X is what percent of Y?
30 is 25% of 120
30 ÷ 120 × 100 = 25%
Percentage increase or decrease
30% increase
(65 − 50) ÷ |50| × 100 = 30%
The value changed by 15, from 50 to 65.
Percentage difference between two numbers
40% difference
|40 − 60| ÷ ((|40| + |60|) ÷ 2) × 100 = 40%
Compares the gap to the average of both numbers, so the order doesn’t matter.
Increase or decrease a number by a percentage
80 + 15% = 92
80 × (1 + 15 ÷ 100) = 92
That's a rise of 12. Useful for prices, discounts and pay rises.
How to use the Percentage Calculator
- Find the calculator that matches your question. Examples are filled in to get you started.
- Replace the example numbers with your own. Decimals and negative numbers are fine.
- The answer updates instantly, with the formula shown underneath so you can check it.
Percentage change vs percentage difference
Percentage change has a direction: it measures how much a value went up or down compared with where it started. If a price goes from 50 to 65, that's a 30% increase. Going back from 65 to 50 is a 23.08% decrease, not 30%, because the starting point is different.
Percentage difference has no direction. It compares the gap between two numbers with their average, which suits comparing two measurements where neither is the “original”. It's normally used with positive numbers.
A common mistake with discounts
A 20% discount followed by another 20% discount is not 40% off. The second discount applies to the already reduced price: 100 → 80 → 64, which is 36% off in total. You can check this with the last calculator above.
Why can't I calculate a change from 0?
Percentage change divides by the starting value. If you start at 0, any increase is infinitely large in percentage terms, so there's no meaningful answer. In that case, describe the change in plain numbers instead, for example “up from 0 to 25”.
Want to learn more? Read our guide: How to calculate percentage increase (and decrease)