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Percentage Calculator

Work out percentages quickly: percentage of an amount, what percentage one figure is of another, increases and discounts.

4 types of calculation Instant result 100% free

Type of calculation

Percentage
%

Result

30
20% of 150
Amount150
Percentage20%
Result30

The 4 percentage formulas

Learn how to work out any type of percentage with these basic formulas

Percentage of an amount

Most used

Works out how much a percentage of an amount is. Multiply the amount by the percentage divided by 100.

Formula
Result = Amount × (Percentage / 100)
Example: 20% of 150 = 150 × 0.20 = 30

What percentage is it

Comparisons

Find out what percentage a part represents of the total. Divide the part by the total and multiply by 100.

Formula
Percentage = (Part / Total) × 100
Example: 30 of 150 = (30/150) × 100 = 20%

Increase by a percentage

Rises

Works out the result of increasing an amount by a percentage. Handy for pay rises, inflation, and so on.

Formula
Result = Amount × (1 + Percentage/100)
Example: 100 + 15% = 100 × 1.15 = 115

Decrease by a percentage

Discounts

Works out the result of applying a discount. Perfect for sales, discounts and special offers.

Formula
Result = Amount × (1 - Percentage/100)
Example: 100 - 25% = 100 × 0.75 = 75

Frequently asked questions about percentages

We answer the most common questions about working out percentages

Multiply the amount by 0.20 (or divide by 5). For example: 20% of 80 = 80 × 0.20 = 16. Quick tip: 20% is the same as dividing by 5.
Divide the part by the total and multiply by 100. For example: what % is 25 of 200? (25 / 200) × 100 = 12.5%
To add 20% VAT, multiply the price by 1.20. For example: £100 + VAT = 100 × 1.20 = £120. For the reduced rate of 5%, multiply by 1.05.
10% of any number is simply moving the decimal point one place to the left. 10% of 250 = 25. From there you can work out others: 5% = half of 10%, 15% = 10% + 5%, 20% = 10% × 2.
Discounts do NOT add up directly. 20% plus an extra 10% is not 30%. They are applied one after the other: 100 × 0.80 = 80, then 80 × 0.90 = 72. The total discount is 28%, not 30%.
Subtract the old value from the new one, divide by the old value and multiply by 100. Example: from 80 to 100 = ((100-80)/80) × 100 = 25% increase.

How to work out percentages: a complete guide

Working out percentages is one of the most widely used pieces of maths in everyday life. From calculating discounts in a shop to understanding the rise in the cost of living, working out the VAT on an invoice or knowing how much of your salary goes on tax, percentages are everywhere. This calculator lets you carry out the four most common types of percentage sum instantly.

A percentage represents a fraction of 100. When we say "25%", we mean "25 out of every 100" or "a quarter". The symbol % comes from the Latin "per centum" (per hundred). Understanding percentages will help you make better financial decisions and interpret statistics.

Common percentages and their equivalents

Memorising these equivalents will let you do quick mental sums without a calculator:

Percentage Fraction Decimal Trick to work it out
50% 1/2 0.50 Divide by 2 (half)
25% 1/4 0.25 Divide by 4 (a quarter)
20% 1/5 0.20 Divide by 5
10% 1/10 0.10 Move the decimal point one place to the left
5% 1/20 0.05 Work out 10% and divide by 2
1% 1/100 0.01 Move the decimal point two places to the left
33.33% 1/3 0.333... Divide by 3 (a third)
75% 3/4 0.75 Work out 25% and subtract it from the total

Quick tip: how to work out 15% in your head

15% is handy for working out a service charge. Do it in 3 steps:

  1. Work out 10% (move the decimal point to the left)
  2. Work out half of that 10% (that is the 5%)
  3. Add the two results together = 15%

Example: 15% of £80 = 10% (8) + 5% (4) = £12

Practical uses of percentages

Percentages are used constantly in everyday and professional life. These are the most common situations where you will need to work out percentages:

Discounts and sales

Working out the final price of a product with 30% off, or knowing how much you save in the Black Friday sales.

Tax (VAT, Income Tax)

Adding 20% VAT to a price, working out your Income Tax or determining how much tax you pay on your earnings.

Pay rises and price increases

Working out what a 3% pay rise will mean for your salary, or how much your rent will go up with the annual review.

Statistics and proportions

Knowing what percentage of your budget you spend on each category, or interpreting survey and study data.

Key percentages in personal finance

These are the most important percentages you should know to manage your money better:

Concept Percentage What it means
Standard VAT rate 20% Tax on most goods and services
Reduced VAT rate 5% Domestic fuel and power, children's car seats
Zero VAT rate 0% Most food, books, newspapers, children's clothes
Basic rate of Income Tax 20% Tax on income above the personal allowance
Maximum mortgage affordability 30-35% The most your repayment should be relative to income
Saving rule (50/30/20) 20% Ideal percentage to set aside for monthly savings
Historical stock market return ~7-10% Average annual return of indices such as the S&P 500

Common mistakes when working out percentages

Adding percentages directly

A 10% increase followed by another 10% is not a 20% total. It is 21% (1.10 × 1.10 = 1.21). Percentages multiply, they do not add.

Believing that the same % up and down cancels out

If something goes up 50% and then down 50%, it does not return to the original value. Example: 100 + 50% = 150, then 150 - 50% = 75 (not 100).

Working out the percentage on the wrong base

To find out by what % something increased, divide the increase by the ORIGINAL value, not the new one. (New - Original) / Original × 100.

Note: This percentage calculator is a general-purpose tool. For specific financial calculations such as tax, VAT or mortgages, we recommend using our dedicated calculators.

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