Percentage Calculator

Use this percentage calculator to work out percentage increase, percentage decrease, discounts, markups, percentage difference and what one number is as a percentage of another.

Common percentage calculations

• Find 20% of a number for VAT, tips or discounts.
• Calculate a percentage increase for rent, salary, prices or bills.
• Calculate a percentage decrease for sales, reductions and savings.
• Compare two values using percentage difference.

Percentage increase formula

Percentage increase = ((new value – old value) / old value) x 100. For example, if a bill rises from GBP 80 to GBP 100, the increase is GBP 20. GBP 20 divided by GBP 80 equals 0.25, so the increase is 25%.

Percentage decrease formula

Percentage decrease = ((old value – new value) / old value) x 100. This is useful for discounts, price drops and reductions.

Related calculators

You may also need the VAT calculator, discount calculator, salary calculator or loan calculator.

Percentage Calculator FAQs

How do I calculate 20% of a number?

Multiply the number by 0.20. For example, 20% of 50 is 10.

How do I add 20% to a price?

Multiply the price by 1.20. For example, GBP 100 plus 20% equals GBP 120.

How do I remove 20% from a price?

Multiply the price by 0.80. If the price includes VAT and you want the net price, divide by 1.20 instead.