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WAVESPEED AI PERCENTAGE CALCULATOR Works in your browser
100% FREE

Free Percentage CalculatorEvery common percent question, answered as you type.

Fill in the numbers in plain sentences – what is 15% of 80, 30 is what percent of 120, the change from 50 to 65 – and read the answer right away.
Each answer shows the working, so you can check it or copy it.

Live answersShows the working8 question types
No sign-up Unlimited use Remembers your numbers
Results update as you type.

Percent of a number

What is
of
?
12

15 ÷ 100 × 80 = 12

What percent

 is what percent of
?
25%

30 ÷ 120 × 100 = 25%

Find the whole

 is
of what?
120

30 ÷ 25 × 100 = 120

Percentage change

From
to
is a change of?
+30% (increase)

(65 − 50) ÷ |50| × 100 = 30%

Increase by a percent

 increased by
is?
92

80 × (1 + 15 ÷ 100) = 92, that is 12 more

Decrease by a percent

 decreased by
is?
68

80 × (1 − 15 ÷ 100) = 68, that is 12 less

Percentage difference

Difference between
and
?
40%

|10 − 15| ÷ ((10 + 15) ÷ 2) × 100 = 40%

Value before a change

After a change of
the value is
. What was it before?
80

92 ÷ (1 + 15 ÷ 100) = 80

Calculated on your device. What you type is not sent anywhere.
THREE SIMPLE STEPS

How to calculate percentages

01

Pick the question

Find the sentence that matches what you want to know: a percent of a number, a percentage change and so on.

02

Fill in the numbers

Type into the boxes in the sentence. Decimals and negative numbers work.

03

Read the answer

The answer and its working update as you type. Copy it with one click.

Worked examples

A tip

What is 15% of an $80 bill?

  1. 15 ÷ 100 = 0.15.
  2. 0.15 × 80 = 12.

$12 – so $92 with the tip.

A test score

You got 30 out of 120 points. What percent is that?

  1. 30 ÷ 120 = 0.25.
  2. 0.25 × 100 = 25.

25%.

A price rise

A price went from $50 to $65. By how much did it rise?

  1. The change: 65 − 50 = 15.
  2. 15 ÷ 50 = 0.3, × 100 = 30.

A 30% increase.

Taking off sales tax

You paid $92 including 15% tax. What was the price before tax?

  1. 92 ÷ (1 + 15 ÷ 100) = 92 ÷ 1.15.

$80 before tax.

Percentage formulas

P% of Y = P ÷ 100 × YX as a percent of Y = X ÷ Y × 100% change = (new − old) ÷ |old| × 100Y ± P% = Y × (1 ± P ÷ 100)

A percent is a number out of 100: 15% means 15 ÷ 100 = 0.15. Percentage change compares the new value with the old one; percentage difference compares two values with their average, when neither is the starting point.

Raising a number by 10% and then lowering the result by 10% does not give the starting number back: 100 → 110 → 99.

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Percentage Calculator FAQ

How do I calculate a percentage of a number?

Divide the percent by 100 and multiply by the number. 15% of 80 is 15 ÷ 100 × 80 = 12.

How do I find what percent one number is of another?

Divide the part by the whole and multiply by 100. 30 out of 120 is 30 ÷ 120 × 100 = 25%.

How is percentage change calculated?

Subtract the old value from the new one, divide by the old value and multiply by 100. From 50 to 65 is (65 − 50) ÷ 50 × 100 = 30%. A negative result is a decrease.

What is the difference between percentage change and percentage difference?

Percentage change measures a move from an old value to a new one. Percentage difference compares two values that are on an equal footing, by dividing the gap by their average: between 10 and 15 it is 5 ÷ 12.5 × 100 = 40%.

How do I remove a percentage, like tax, from a total?

Divide the total by 1 plus the percent as a decimal. $92 including 15% tax is 92 ÷ 1.15 = $80. Use the Value before a change card.

Why can't I divide by zero?

Some questions have no answer for zero: no number is “what percent of 0”, and a change from 0 has no percentage. The card says so instead of showing a wrong number.

Is it free?

Yes. No sign-up, no limits. It works in your browser and remembers your numbers.

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