Percentage Calculator
Percentages of a value, ratios, and increase or decrease.
About this calculator
The percentage calculator covers the three percentage questions that come up in daily life: what is X% of Y (15% of a 2,400 bill), X is what percentage of Y (scoring 42 out of 60), and the percentage change between two values (a price going from 250 to 290). Pick the mode, enter two numbers, and the result appears instantly.
Percentage change works for both directions — an increase comes out positive and a decrease negative — so the same mode answers 'how much did it grow?' and 'how much did it drop?'.
Frequently asked questions
How do I calculate X% of a number?
Multiply the number by the percentage and divide by 100. 15% of 200 is 200 × 15 ÷ 100 = 30. The 'X% of Y' mode does exactly this.
How do I work out a percentage increase?
Subtract the old value from the new value, divide by the old value, then multiply by 100. Going from 250 to 290 is (290 − 250) ÷ 250 × 100 = a 16% increase. Use the 'percentage change' mode with the old and new values.
How do I work out a percentage decrease?
The same formula with the values falling: (new − old) ÷ old × 100. Going from 80 to 60 gives (60 − 80) ÷ 80 × 100 = −25%, i.e. a 25% decrease.
What percentage is one number of another?
Divide the part by the whole and multiply by 100. 42 out of 60 is 42 ÷ 60 × 100 = 70%. That's the 'X is what % of Y' mode.