Percentage Increase / Decrease Calculator
Apply a percentage to a number — add it on or take it off. Enter the value and the percent to get the new amount, plus the exact size of the change. Handy for markups, discounts, tips and raises.
Your numbers
Result
- Amount added / removed
- 20
| Item | Value |
|---|---|
| Starting value | 200 |
| Amount added (10%) | +20 |
| Result | 220 |
How to increase a number by a percentage
Multiply the value by (1 + percent ÷ 100). To add 10% to 200: 200 × 1.10 = 220. Equivalently, work out 10% of 200 (which is 20) and add it on. This is how you apply a markup, a raise or sales tax.
How to decrease a number by a percentage
Multiply by (1 − percent ÷ 100). To take 10% off 200: 200 × 0.90 = 180. This is the discount case — a "30% off" price is the original times 0.70. Switch the direction field to subtract instead of add.
The compounding trap
Adding a percentage and then removing the same percentage does not return the original value, because the second percentage applies to a different base. 200 up 10% is 220; 220 down 10% is 198, not 200. Stacking discounts works the same way — "20% off then 10% off" is not 30% off.
Frequently asked questions
Sources
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