Boring Tools

Percentage Calculator

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Calculate percentages, increases, and decreases.

Three percentage questions answered on one page: what is X% of Y, X is what percent of Y, and by what percentage did a number change. Every answer updates as you type.

How it works

The three sections use these formulas, and every result is rounded to two decimal places:

X% of Y = X ÷ 100 × Y. X is what percent of Y = X ÷ Y × 100. Percentage change from X to Y = (Y − X) ÷ X × 100, shown with a + when it is an increase and a − when it is a decrease.

How to use it

  1. Find the section that matches your question.
  2. Enter the two numbers in its boxes.
  3. Read the answer in the result box under them. Use Copy to copy the sentence.

Options & controls

What is X% of Y?

X (%)
The percentage, for example 20 for 20%. Default: 20.
Y
The number to take the percentage of. Default: 150.
Result
A sentence such as “20% of 150 = 30”. Shows a dash if either box is empty or not a number.

X is what percent of Y?

X
The part. Default: 30.
Y
The whole. Cannot be 0. Default: 150.
Result
A sentence such as “30 is 20% of 150”. Shows a dash if Y is 0 or either box is empty.

Percentage change from X to Y

From (X)
The starting value. Cannot be 0. Default: 100.
To (Y)
The ending value. Default: 120.
Result
A sentence such as “+20% change” for a rise or “-25% change” for a fall. Shows a dash if From is 0 or a box is empty.

Buttons

Copy
Beside each result. Copies that result sentence.
Reset
In the title row. Restores all six boxes to the sample values.

Tips & guidelines

  • Percentage change and percentage points are not the same. If a rate rises from 4% to 6%, that is 2 percentage points but a 50% change.
  • A rise followed by an equal fall does not cancel out: +20% then −20% leaves you 4% below where you began. To undo a +20% rise, you need a fall of about 16.67%.
  • To add a percentage to a price (for example, tax), the result of “X% of Y” is the amount to add. The Discount Calculator is better suited to sale prices.
  • Decimals are welcome: 7.5 is 7.5%.

Limits

  • The answer is rounded to two decimal places, so very small or very precise figures lose detail.
  • If the “From” value is negative, the percentage change is measured against that negative number as entered, which flips the usual meaning of + and −. It is best used with positive numbers.
  • The three sections work independently; they do not feed into each other.

Saved in your browser

Nothing. Values return to the sample numbers when you refresh.

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