Percentage Calculator
Seven types of percentage calculation in one tool — percent of, increase, decrease, percent change, and more.
Runs entirely in your browser. Nothing is sent to our servers.
About this tool
Seven percentage calculations in one tool. Pick the type of problem you're solving, enter your two numbers, and see the result instantly.
Which mode to use
- What is X% of Y?
- For discounts and shares. "What's 20% of $80?" → 16.
- X is what percent of Y?
- For ratios and proportions. "15 out of 60 is what percent?" → 25%.
- X increased by Y%
- For markups and raises. "$100 increased by 8%" → $108.
- X decreased by Y%
- For discounts and markdowns. "$50 decreased by 30%" → $35.
- Percent change from X to Y
- For comparing before and after. "From $80 to $100" → +25%.
- X + Y (and as a percent)
- For adding amounts and seeing the percentage. "$200 + $30" → $230, +15%.
- X − Y (and as a percent)
- For subtracting amounts and seeing the percentage. "$200 − $30" → $170, −15%.
Frequently asked questions
- Why does a 50% increase followed by a 50% decrease not return to the original?
- Because the second percent is calculated on the new (larger) number. $100 + 50% = $150. $150 − 50% = $75. Not $100. It's a common gotcha — to undo a 50% increase, you actually need a 33.3% decrease.
- What's the difference between "X + Y" and "X increased by Y%"?
- In "X + Y", Y is an absolute amount. In "increased by Y%", Y is a percentage of X. So 100 + 15 = 115, but 100 increased by 15% = 115 (coincidence for these numbers). Try 200: 200 + 15 = 215, but 200 increased by 15% = 230.
- Why is the answer sometimes negative?
- When X is bigger than Y in "percent change from X to Y", the change is negative — a decrease. "From 100 to 80" is −20%.
Last updated: May 17, 2026