How do I calculate a percentage discount?

Multiply the original price by the discount percentage, then divide by 100. That gives you the saving. Subtract the saving from the original price to get the sale price. For example: 25% off £60 means a saving of £15, so the sale price is £45.

What is 20% off £85?

20% of £85 is £17. Take that away and you pay £68. The calculation: £85 × 20 ÷ 100 = £17 saving; £85 − £17 = £68 sale price.

How do I find the original price after a discount?

Divide the sale price by one minus the discount expressed as a decimal. If an item costs £70 after a 30% discount, the original price is £70 ÷ 0.70 = £100. You cannot find the original by simply adding the discount percentage back onto the sale price, because the retailer took the discount from the original price, not from the reduced amount.

Is 20% off then 10% off the same as 30% off?

No. When a retailer applies two discounts in sequence, the second applies to the already-reduced price, not to the original. The result is 28% off, not 30%. On a £100 item: after 20% off you pay £80; then 10% off £80 is £8; final price £72, total saving £28.

How do I work out what percentage off a sale price is?

Subtract the sale price from the original price to find the saving. Then divide the saving by the original price and multiply by 100. For example: original £80, sale price £60. Saving = £20. £20 ÷ £80 × 100 = 25% off.

What is the formula for a discount?

Sale price = Original price × (1 − Discount% ÷ 100). For the saving alone: Saving = Original price × Discount% ÷ 100. To find the discount percentage when you have both prices: Discount% = ((Original − Sale) ÷ Original) × 100.

How do I calculate a percentage discount?

Multiply the original price by the discount percentage, then divide by 100. That gives you the saving. Subtract the saving from the original price to get the sale price. For example: 25% off £60 means a saving of £15, so the sale price is £45.

What is 20% off £85?

20% of £85 is £17. Take that away and you pay £68. The calculation: £85 × 20 ÷ 100 = £17 saving; £85 − £17 = £68 sale price.

How do I find the original price after a discount?

Divide the sale price by one minus the discount expressed as a decimal. If an item costs £70 after a 30% discount, the original price is £70 ÷ 0.70 = £100. You cannot find the original by simply adding the discount percentage back onto the sale price, because the retailer took the discount from the original price, not from the reduced amount.

Is 20% off then 10% off the same as 30% off?

No. When a retailer applies two discounts in sequence, the second applies to the already-reduced price, not to the original. The result is 28% off, not 30%. On a £100 item: after 20% off you pay £80; then 10% off £80 is £8; final price £72, total saving £28.

How do I work out what percentage off a sale price is?

Subtract the sale price from the original price to find the saving. Then divide the saving by the original price and multiply by 100. For example: original £80, sale price £60. Saving = £20. £20 ÷ £80 × 100 = 25% off.

What is the formula for a discount?

Sale price = Original price × (1 − Discount% ÷ 100). For the saving alone: Saving = Original price × Discount% ÷ 100. To find the discount percentage when you have both prices: Discount% = ((Original − Sale) ÷ Original) × 100.

Percent Off Calculator

Standing in a shop with a "20% off" sign and no idea what you will actually pay? This calculator does the maths in seconds. Three modes: find the sale price, find the discount percentage, or recover the original price. There is also a stacked discount tool for when a retailer applies two separate discounts in sequence.

Currency:

Original price

The price before the discount

Discount %

The percentage being taken off

Quick:

Stacked discount calculator — when two discounts are applied in sequence

Original price

First discount %

Applied to the original price

Second discount %

Applied to the already-discounted price

How to use this calculator

What do I pay? Enter the original price and the discount percentage. The calculator shows the sale price and how much you save. Use the quick-select buttons for common discount amounts.

What % off is that? Enter the original price and the sale price. Useful when a retailer shows "was £80, now £60" and you want to know the actual percentage off.

What was the original price? Enter the sale price and the discount percentage. The calculator works backwards to the price before the discount, useful when checking receipts or comparing deals.

Stacked discount calculator: open the stacked discount panel at the bottom of the calculator to find the true total when two discounts are applied one after the other.

Formula

Sale price:

Sale = Original × (1 − Discount% ÷ 100)

Discount percentage:

Discount% = ((Original − Sale) ÷ Original) × 100

Original price:

Original = Sale ÷ (1 − Discount% ÷ 100)

Stacked discounts:

Final = Original × (1 − D1÷100) × (1 − D2÷100)

Worked examples

A jacket at £85, reduced by 20%

85 × (1 − 20÷100) = £68 (saving £17)

A laptop was £649, now £551.65. What is the discount?

((649 − 551.65) ÷ 649) × 100 = 15% off

Item costs £56 after a 30% discount. Original price?

56 ÷ (1 − 30÷100) = 56 ÷ 0.70 = £80

£100 item: 20% off, then 10% off

100 × 0.80 × 0.90 = £72 (28% total, not 30%)

How it works

When a retailer discounts something, they take a percentage of the original price and subtract it. The formula is straightforward: multiply the original price by the discount percentage, divide by 100 to get the saving, then subtract that saving from the original price.

The trickier calculation is finding the original price when all you have is the sale price and the discount percentage. The instinct most people have is to add the discount percentage back on. That gives the wrong answer, because the retailer calculated the discount from the original price, not from the reduced one. The correct method is to divide the sale price by one minus the discount fraction: Original = Sale ÷ (1 − Discount% ÷ 100).

Stacked discounts work the same way but applied twice. The key point is that the second discount applies to the already-reduced price, not the original. Two successive 10% discounts is not the same as one 20% discount: it is actually 19%. The more discounts are stacked, the more this gap compounds.

Common uses

Checking what you will pay before you reach the checkout during a sale
Comparing two on-sale items to find out which is the better deal
Working out the real total when a retailer advertises two discounts in sequence
Finding the original price of an item that only shows a sale tag
Calculating how much you are saving across a basket of discounted items
Verifying that an advertised discount percentage matches the prices shown
Estimating Black Friday savings before committing to a purchase
Working out the percentage discount on second-hand goods where only two prices are known

Frequently asked questions

: Multiply the original price by the discount percentage, then divide by 100. That gives you the saving. Subtract the saving from the original price to get the sale price. For example: 25% off £60 means a saving of £15, so the sale price is £45.
: 20% of £85 is £17. Take that away and you pay £68. The calculation: £85 × 20 ÷ 100 = £17 saving; £85 − £17 = £68 sale price.
: Divide the sale price by one minus the discount expressed as a decimal. If an item costs £70 after a 30% discount, the original price is £70 ÷ 0.70 = £100. You cannot find the original by simply adding the discount percentage back onto the sale price, because the retailer took the discount from the original price, not from the reduced amount.
: No. When a retailer applies two discounts in sequence, the second applies to the already-reduced price, not to the original. The result is 28% off, not 30%. On a £100 item: after 20% off you pay £80; then 10% off £80 is £8; final price £72, total saving £28.
: Subtract the sale price from the original price to find the saving. Then divide the saving by the original price and multiply by 100. For example: original £80, sale price £60. Saving = £20. £20 ÷ £80 × 100 = 25% off.
: Sale price = Original price × (1 − Discount% ÷ 100). For the saving alone: Saving = Original price × Discount% ÷ 100. To find the discount percentage when you have both prices: Discount% = ((Original − Sale) ÷ Original) × 100.

Related calculators

Reverse Percentage Calculator → Works out what a number was before any percentage was added or removed. Percentage Decrease Calculator → Calculates the percentage drop between any two numbers. Tip Calculator → Works out tip amounts and splits the total between any number of people.

Last reviewed: May 2026