Percentage Calculator
Work out a discount, a price change, a margin, or any other percentage in seconds — five tools on one page.
What is X% of Y?
20% of 150 is 30.
Results update as you type.
Formula
Each tab uses a single one-line formula:
- % of:
result = (percent / 100) × value - What %:
percent = (part / whole) × 100 - % change:
percent = ((to − from) / from) × 100 - Add / Subtract %:
result = value × (1 ± percent / 100) - Reverse %:
original = result / (percent / 100)
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Frequently asked questions
How do I work out a percentage discount?▾
Use the Add/Subtract % tab. Enter the original price as the value and the discount as the percentage, then choose 'subtract'. For example, 20% off £150 is £150 − 20% = £120. The calculator also shows the saving — in this case, £30.
What's the difference between a percentage and percentage points?▾
A percentage is a relative change; a percentage point is an absolute one. Going from 5% to 8% is a 3 percentage-point increase, but a 60% relative increase. The % change tab on this calculator works in relative terms — feed in 5 and 8 and you'll get +60%.
How do I reverse a percentage to find the original number?▾
Use the Reverse % tab. If a sale price of £60 represents 75% of the original, the original was £60 ÷ 0.75 = £80. This is also useful for working backwards from a VAT-inclusive price to the net price.
Can I use this for VAT calculations?▾
Yes for the basic 20% maths — add 20% with the Add/Subtract tab, or work backwards with Reverse %. For a dedicated tool that flags zero-rated and reduced-rate bands, use our VAT Calculator (coming soon as part of this site).
Are negative percentages allowed?▾
Yes. A negative percentage in the Add/Subtract tab is treated as a subtraction — 100 + (−20)% gives the same answer as 100 − 20% (both produce 80). The % change tab returns a signed result so a drop from 100 to 50 reads as −50%.