Percentage Calculator
Calculate percentages three ways: find a percentage of a number, convert part of a whole into a percent, or measure percentage change.
Percentage Calculator
Calculate percentages three ways: find a percentage of a number, convert part of a whole into a percent, or measure percentage change.
How to use the Percentage Calculator
- Enter the percentage and the number it applies to.
- Select the calculation mode: "X% of Y", "X is what % of Y", or "% change".
- Click Calculate to see the result.
Formula
X% of Y = (X / 100) × Y
X is what % of Y = (X / Y) × 100
% change = ((New − Old) / |Old|) × 100
Example
What is 15% of 240? (15 ÷ 100) × 240 = 0.15 × 240 = 36
Step-by-step calculation
- Convert 15% to a decimal: 15 ÷ 100 = 0.15.
- Multiply by the whole: 0.15 × 240 = 36.
- Answer: 15% of 240 is 36.
Real-world uses
- Discount and sale price calculations.
- Tax and tip computation.
- Academic grading and test scores.
Common mistakes
- Forgetting to divide the percentage by 100 before multiplying.
- Confusing "part" and "whole" when finding what percentage one number is of another.
- Using absolute difference instead of relative difference in percentage change calculations.
Frequently asked questions
Can percentages exceed 100%?
Yes. If a value doubles, the new value is 200% of the original.
What is the difference between a percentage and a percentage point?
A percentage point is the arithmetic difference between two percentages. Going from 10% to 15% is a 5 percentage point increase, which is a 50% relative increase.
How do I find the original price before a discount?
Divide the discounted price by (1 − discount rate as a decimal). Example: $80 after a 20% discount → $80 ÷ 0.80 = $100.