Percentage Calculator

Calculate percentages the easy way

This free percentage calculator handles the three questions people ask most: what is X% of a number, what percentage one number is of another, and the percentage increase or decrease between two values. Pick a mode, type your numbers, and the answer updates instantly - no signup, nothing uploaded.

Everyday uses

• Working out a discount or a tip.
• Checking a test score or a growth rate.
• Comparing prices and changes over time.

The three percentage questions

Almost every percentage problem is one of three shapes. What is X percent of Y: multiply Y by X and divide by 100, so 15 percent of 240 is 36. X is what percent of Y: divide X by Y and multiply by 100, so 30 out of 120 is 25 percent. Percentage change from A to B: subtract, divide by the original A, multiply by 100, so going from 80 to 100 is a 25 percent increase.

The mistake everyone makes

Percentage change is always measured against the starting value. A rise from 100 to 150 is a 50 percent increase, but the fall back from 150 to 100 is only a 33 percent decrease, because the base changed. This is why a 50 percent loss needs a 100 percent gain to recover, a point that matters in discounts, salaries and investments alike.

Common uses

• Discounts, tax and tip amounts while shopping
• Marks and grade percentages from raw scores
• Salary raises and price change comparisons
• Interest, profit margins and statistics homework

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Frequently asked questions