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Percentage Calculator

Pick the question you have, enter two numbers and get the answer: a percentage of a number, a percentage change, an increase or a decrease.

Enter your values

Result

Result
30

How to use Percentage Calculator

  1. Choose the question that matches yours, such as X% of Y or percentage change.
  2. Enter the two numbers. The labels change to match the question.
  3. Read the answer, which updates as you type.

About this tool

A percentage is a fraction out of 100, so 15% is 15 out of every 100, or 0.15. Nearly every percentage question is one of six: a percentage of a number, what percentage one number is of another, the percentage change between two values, the whole when you know a part and its percentage, and increasing or decreasing a number by a percentage.

Percentage change is calculated against the starting value. Going from 50 to 75 is a 50% rise. Going from 75 back to 50 is a fall of only 33.3%, because the starting value is now 75. This is why a rise and a fall of the same percentage do not cancel out.

Increasing a number by a percentage multiplies it by 1 plus the percentage as a decimal, and decreasing it multiplies by 1 minus the percentage. A price of 200 with 10% added is 220, and with 25% taken off it is 150.

How it is calculated

X% of Y = X ÷ 100 × Y. X is what percent of Y = X ÷ Y × 100.

Percentage change = (new − old) ÷ old × 100. Whole from a part = part ÷ (percent ÷ 100).

Increase by P% = number × (1 + P ÷ 100). Decrease by P% = number × (1 − P ÷ 100).

Worked examples

  • 15% of 200 is 30.
  • 30 is 15% of 200.
  • From 50 to 75 is a 50% rise, but from 75 to 50 is a -33.3% change.
  • 200 increased by 10% is 220, and decreased by 25% is 150.

Tips for better results

  • For a discount, use decrease by a percentage. For tax on top of a price, use increase.
  • When comparing two values, say which one is the starting value before you work out the percentage change.
  • Two percentage changes in a row are not the same as adding them. Apply one after the other.

Frequently asked questions

How do I calculate a percentage of a number?

Divide the percentage by 100 and multiply by the number. For 15% of 200 that is 0.15 × 200 = 30.

How do I calculate percentage change?

Subtract the old value from the new value, divide by the old value and multiply by 100.

Why is a 50% rise followed by a 50% fall not back to the start?

The fall is taken from the higher value. 100 up 50% is 150, and 150 down 50% is 75.

Can I find the original price before a discount?

Yes. Use the question X is Y% of what number, with the discounted price as X and the percentage paid as Y.

Are my numbers saved or sent anywhere?

No. The calculation runs in your browser on your own device. Nothing you type is sent to Paul Digital or any other server.

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Privacy

The calculation runs in your browser on your own device. The numbers you type are not sent to Paul Digital or any other server. Results are estimates from the numbers you enter and are not financial, tax or legal advice.