Percentage calculations come up constantly in daily life — discounts, taxes, tips, grades, investment returns, and statistics all use percentages. Yet they trip people up because our brains are not wired for proportional thinking. What is 15% of $85? Is a 40% discount followed by an additional 20% off the same as 60% off? (No — it is actually 52% off.) This calculator handles all common percentage operations: finding a percentage of a number, calculating what percentage one number is of another, and finding percentage increase or decrease between two values.
Percentage Calculator
Calculate percentages, percentage change, and percentage of a number.
How to Use This Calculator
- Choose your calculation type — percentage of a number, percentage change, or what percent X is of Y
- Enter your numbers in the appropriate fields
- View the result instantly along with the formula used
- Use percentage change mode to calculate discounts, markups, growth rates, or any before-and-after comparison
- Try reverse calculations — if an item costs $60 after a 25% discount, the original price was $80
How It Works
This percentage calculator uses standard formulas to provide accurate results.
The basic rule:
- Result = Number × Percentage / 100
Tax laws and financial markets change frequently. Verify current rates with your financial institution.
Tips & Considerations
- Percentage increase and decrease are not symmetrical. A 50% increase followed by a 50% decrease does not bring you back to the start — it leaves you at 75% of the original.
- To quickly calculate 15% of anything: find 10% (move the decimal one place left), then add half of that. 15% of $80 = $8 + $4 = $12.
- Successive discounts multiply, they do not add. A 30% off coupon plus a 20% off sale equals 44% total discount, not 50%.
- When comparing growth rates, use percentage points for absolute differences and percent for relative differences. Going from 5% to 10% is a 5 percentage point increase but a 100% relative increase.
Frequently Asked Questions
How do I calculate a percentage?
Multiply the number by the percentage and divide by 100. For example, 15% of 200 = 200 × 15 / 100 = 30.
How do I find what percentage one number is of another?
Divide the part by the whole and multiply by 100. For example, 30 is what % of 200? 30/200 × 100 = 15%.
How do I calculate percentage change?
(New Value - Old Value) / Old Value × 100. An increase from 200 to 230 = (230-200)/200 × 100 = 15% increase.
What is a percentage point vs percentage?
A percentage point is an absolute difference. Going from 5% to 8% is a 3 percentage point increase, but a 60% percentage increase.