Percentage calculator
The five most common percentage questions. Type your numbers into the sentence, and the working appears under each answer.
What is% of?
15 ÷ 100 × 200 = 30
is what percent of?
30 ÷ 200 × 100% = 15%
What is the percentage change fromto?
increase
(250 − 200) ÷ 200 × 100% = +25%
by%
200 + 15% × 200 = 230
What was the value beforeof%, if it is now?
123 ÷ 1.2 = 102.5
Percentage formulas
| Question | Formula | Example |
|---|---|---|
| What is p% of y? | p ÷ 100 × y | 15% of 200 = 30 |
| x is what percent of y? | x ÷ y × 100% | 30 of 200 = 15% |
| Percentage change from a to b | (b − a) ÷ a × 100% | 200 → 250 = +25% |
| y increased by p% | y × (1 + p ÷ 100) | 200 + 15% = 230 |
| Value before an increase of p% | result ÷ (1 + p ÷ 100) | 120 ÷ 1.2 = 100 |
Adding and removing VAT
To add VAT, use the fourth question: 100 increased by 20% is 120. To remove VAT from a price, use the last question with the VAT 20% button: 120 including VAT is 100 before tax. The tax itself is the difference, here 20.
Percent versus percentage points
When you compare two values that are already percentages, the difference is measured in percentage points. If unemployment falls from 6% to 4.5%, it falls by 1.5 percentage points, but by 25% in relative terms. The third question calculates that relative change.
Common questions
How do I calculate 15% of a number?
Divide the percentage by 100 and multiply by the number: 15% of 200 is 15 ÷ 100 × 200 = 30. A quicker way is to multiply the number by 0.15.
How do I work out a percentage increase?
Subtract the old value from the new one, divide by the old value and multiply by 100%. A price going from 200 to 250 is (250 − 200) ÷ 200 × 100% = a 25% increase.
How do I remove VAT from a price?
Divide the price including VAT by 1 + the VAT rate. At 20% VAT, 120 ÷ 1.2 = 100 before tax. In the calculator, use the last question with the VAT 20% button.
Why doesn’t a 20% discount undo a 20% increase?
Because each percentage is taken from a different amount. 100 increased by 20% is 120, and 20% of 120 is 24, so after the discount you have 96.
What is the difference between percent and percentage points?
A percentage point is the difference between two values that are already percentages. If an interest rate rises from 5% to 6%, it rises by 1 percentage point, which is a 20% increase.