Percentage Calculator
To find a percentage of a number, multiply the number by the percentage and divide by 100. 15% of 240 = 240 × 15 ÷ 100 = 36. The four calculators below cover the most common percentage questions.
Calculate a percentage
Percentage Calculator
Calculate percentages, percentage changes, increases, decreases and more
What is X% of Y?
Find a percentage of a number.
X is what percentage of Y?
Find what percentage one number is of another number.
Percentage Change
Calculate the percentage increase or decrease between two values.
Percentage Increase / Decrease
Increase or decrease a number by a specific percentage.
The four calculations
1. What is X% of Y?
Result = Y × X ÷ 100
15% of 240 = 36.
2. X is what percent of Y?
Percent = X ÷ Y × 100
30 is 25% of 120.
3. Percentage increase or decrease
Change % = (New − Original) ÷ Original × 100
From 80 to 60: (60 − 80) ÷ 80 × 100 = −25%, a 25% decrease.
4. Increase or decrease a number by X%
Increase: Y × (1 + X ÷ 100) Decrease: Y × (1 − X ÷ 100)
200 increased by 15% = 230; decreased by 15% = 170.
Common mistakes
- Percentage change is not reversible. A 25% drop followed by a 25% rise doesn’t get you back: 100 → 75 → 93.75.
- Percent vs percentage points. An interest rate moving from 4% to 5% is a 1 percentage-point rise but a 25% increase.
- The original value can’t be zero when calculating percentage change.
Everyday uses
Discounts and sale prices, tips, tax, exam scores, salary rises, and growth in sales or traffic. For profit margins on products, see the e-commerce profit calculator.
Percentages in spreadsheets
In Excel or Google Sheets: X% of Y is =Y*X%; percentage change is =(New-Old)/Old formatted as a percentage; increasing by X% is =Y*(1+X%).
Frequently asked questions
Use “decrease by X%”. A $80 item with 25% off costs 80 × 0.75 = $60.
Divide by (1 + rate). If a price including 20% tax is $120, the pre-tax price is 120 ÷ 1.2 = $100.
For change over time, use the increase/decrease calculator. Percentage difference without a starting point is a different formula: |A − B| ÷ ((A + B) ÷ 2) × 100.
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