Percentage Calculator

Five common percentage questions in one place. Fill in the two boxes of the calculator you need and the answer appears as you type. Use it for discounts, tips, taxes, grades and price changes.

What is X% of Y?

X is what percent of Y?

Percentage change from X to Y

Increase a number by a percentage

Decrease a number by a percentage

Runs entirely in your browser. Nothing you enter is sent to a server.

How to use it

  1. Find the calculator that matches your question.
  2. Type the two numbers in its boxes.
  3. Read the result below them. It updates as you type.

Formulas

  • X% of Y = X ÷ 100 × Y
  • X is what percent of Y = X ÷ Y × 100
  • Percentage change = (new − old) ÷ old × 100
  • Increase Y by X% = Y × (1 + X ÷ 100)
  • Decrease Y by X% = Y × (1 − X ÷ 100)
  • Example: a price of 80 with 25% off becomes 80 × (1 − 0.25) = 60.

Frequently asked questions

How do I calculate a discount?
Use “Decrease a number by a percentage”. Enter the discount as the percentage and the original price as the number. The result is the price after the discount.
What is the difference between a percent and a percentage point?
A rate that goes from 10% to 12% rises by 2 percentage points, but by 20% in relative terms. Percentage change compares the new value with the old one.
Why does the percentage change show a plus or minus sign?
A plus sign means the value increased and a minus sign means it decreased. If the starting value is negative, the change is measured against its absolute value.
Why do I get an error when the reference is zero?
Dividing by zero has no result. A percentage of the total only makes sense when the total is not zero, and a change needs a starting value that is not zero.

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