How to work out 20% off a price
The short answer: to take 20% off, multiply the price by 0.8. £50 × 0.8 = £40. In your head: find 10% by moving the decimal point one place left, double it, and take it off. 10% of £50 is £5, so 20% is £10, and the sale price is £40.
20% off common prices
| Price | You save | You pay |
|---|---|---|
| £10.00 | £2.00 | £8.00 |
| £25.00 | £5.00 | £20.00 |
| £39.99 | £8.00 | £31.99 |
| £50.00 | £10.00 | £40.00 |
| £79.00 | £15.80 | £63.20 |
| £120.00 | £24.00 | £96.00 |
| £249.00 | £49.80 | £199.20 |
| £500.00 | £100.00 | £400.00 |
Three ways to do it
- Multiply by 0.8. Fastest on a calculator. For any discount, multiply by (100 − discount) ÷ 100: 15% off is × 0.85, 30% off is × 0.7.
- Find 10% and double it. Easiest in your head. £79: 10% is £7.90, 20% is £15.80, so £63.20.
- Divide by 5. 20% is one-fifth. £120 ÷ 5 = £24 off, so £96.
Other discounts on £100 and £50
| Discount | Multiply by | £100 becomes | £50 becomes |
|---|---|---|---|
| 10% off | 0.90 | £90.00 | £45.00 |
| 15% off | 0.85 | £85.00 | £42.50 |
| 20% off | 0.80 | £80.00 | £40.00 |
| 25% off | 0.75 | £75.00 | £37.50 |
| 30% off | 0.70 | £70.00 | £35.00 |
| 50% off | 0.50 | £50.00 | £25.00 |
Stacked discounts
"20% off, plus an extra 10% at the till" is not 30% off. The second discount comes off the already reduced price:
- £100 with 20% off is £80.
- 10% off £80 is £8, so you pay £72.
- That is 28% off in total: 0.8 × 0.9 = 0.72.
The order doesn't matter: 10% then 20% gives the same £72.
Working backwards
If you know the sale price and want the original, divide by 0.8. A coat at £64 after 20% off was originally £64 ÷ 0.8 = £80. Don't add 20% back on: £64 plus 20% is £76.80, which is wrong.
Discounts compared with other offers
Different offers are easier to compare once you turn them into a percentage off:
| Offer | Works out as |
|---|---|
| Buy one, get one free | 50% off, if you wanted two |
| 3 for 2 | 33.3% off, if you wanted three |
| Buy one, get one half price | 25% off across the two |
| £10 off when you spend £50 | 20% off at exactly £50, less if you spend more |
| 25% extra free | 20% off the price per gram |
The last one catches people out: getting 25% more for the same price is the same as paying 80% of the normal price per unit, so it equals 20% off, not 25%.
20% off and VAT for businesses
If you're VAT-registered and buying something for the business, take the discount off first, then work out the VAT on the reduced price. A £500 + VAT item with 20% off is £400 + £80 VAT = £480. Taking 20% off the VAT-inclusive £600 also gives £480, so the order doesn't change the total, but invoices must show the VAT on the discounted price.
Discount codes and price matching
- Does the code apply to sale items? Many "20% off" codes exclude items already reduced, or apply only above a minimum spend.
- Before or after delivery? Most codes come off the goods only, not postage.
- Cashback on top: cashback sites usually pay a percentage of what you spend after the discount, so 20% off plus 5% cashback is 24% off in total, not 25%.
- Price matching: some retailers will match a competitor's price, which can beat a code. Check their terms.
Working out discounts in your head
- 10%: move the decimal point one place left. £64 → £6.40.
- 5%: half of 10%. £64 → £3.20.
- 15%: 10% plus 5%. £64 → £9.60 off.
- 25%: a quarter: halve it, then halve again. £64 → £16 off.
- 33%: divide by three. £60 → about £20 off.
Is it a real saving?
- Check the "was" price. UK rules require it to be a genuine recent price, but some retailers raise prices before sales.
- Compare with other shops and price history tools.
- 20% off something you didn't need is still 80% spent.
- "Up to 50% off" often means a few items at 50% and most much less.
Not the same as VAT
Taking 20% off is different from removing 20% VAT. To remove VAT, divide by 1.2, which takes off 16.7%. See how to remove VAT from a price. For percentage rises and falls, see how to calculate a percentage increase.
Try the percentage calculator for other sums.
Common questions
How do you work out 20% off?
Multiply the price by 0.8. £50 × 0.8 = £40. Or find 10% by dividing by 10, double it to get 20%, and subtract: 10% of £50 is £5, 20% is £10, so £40.
Is 20% off then another 10% off the same as 30% off?
No. Discounts multiply. 20% off then 10% off is 0.8 × 0.9 = 0.72, so 28% off in total, not 30%.
How do I find the original price before 20% off?
Divide the sale price by 0.8. If something costs £40 after 20% off, the original was £40 ÷ 0.8 = £50.
Is 20% off the same as removing VAT?
No. Removing 20% VAT means dividing by 1.2, which takes off one-sixth (about 16.7%). Taking 20% off takes off one-fifth.