Percentage Calculator
Quick solutions for any percentage problem
What is X% of Y?
Result:
10
What percent is X of Y?
Result:
20%
Percentage change (difference)
Change:
+25%
Add or subtract %
Total:
115
% What is a percent
A percent is one hundredth of a number. Writing 15% means 15 out of 100, that is the fraction 15/100 or 0.15. Percents are used for discounts, taxes, rates, statistics, and comparing values.
The calculator solves four common tasks: find a percent of a number, find what share one number is of another, compute percentage change, and add or subtract a percent. Results update as you type.
📐 Formulas
Percent of a number
Result = Y × X / 100
X as % of Y
Result = X / Y × 100
Percentage change
Result = (New − Old) / |Old| × 100
Add / subtract %
Total = Number ± Number × X / 100
💡 Calculation examples
What is 10% of 100?
100 × 10 / 100 = 10
What percent is 20 of 100?
20 / 100 × 100 = 20%
Change from 80 to 100
(100 − 80) / 80 × 100 = +25%
Add 15% to 100
100 + 100 × 15 / 100 = 115
Subtract 15% from 100
100 − 100 × 15 / 100 = 85
✅ Tips
- To get a discounted price, subtract the percent from the original — e.g. −20% of 1,000 leaves 800.
- To add VAT or a markup, add the percent to the amount — +20% to 1,000 gives 1,200.
- Percentage change is measured from the original “Was” value, not the new one.
- If “Was” is zero, the percent change is undefined — that comparison is invalid.