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Percentage calculator

Calculate percentages, discounts and changes.

Runs in your browser

What do you want to calculate?

You can use a dot or comma as the decimal separator.

Result

16

20 % of 80 is 16.

What it does: Percentage calculator

This calculator answers the four most common percentage questions: what a percentage of an amount is, what percentage one number is of another, how much a value has changed, and what you get after applying an increase or a discount.

Each result comes with a sentence that explains it, so you can double-check it or paste it into a report.

How to use it

  1. Pick the type of calculation with the buttons at the top.
  2. Enter both values; a decimal point or comma both work.
  3. The result and its explanation update instantly.

Examples

Sale price

A £80 jacket with 25 % off: “Add or subtract %” mode, amount 80, percentage 25, Decrease → £60.

Rent increase

Rent goes from 750 to 790: “% change” mode → an increase of 5.33 %.

Test score

You got 42 out of 60 questions right: “What % is it” mode → 70 %.

Limits, formulas and assumptions

  • X % of N = N × X / 100.
  • A as a % of B = A / B × 100 (B can't be 0).
  • Change = (final − start) / |start| × 100.
  • An X % increase followed by an X % decrease does not bring you back: 100 + 10 % = 110; 110 − 10 % = 99.

Frequently asked questions

How do I take 30 % off a price?

Multiply the price by 0.70. In the calculator, choose “Add or subtract %”, enter the price and 30, and select Decrease.

Why is 50 → 100 a 100 % change but 100 → 50 only −50 %?

Because the change is always measured against the starting value, which is different in each case.

Does it handle negative numbers?

Yes. For example, −20 to −10 is a 50 % increase, because it divides by the absolute starting value.

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