Discount Calculator
Use this sale price calculator to work out the final price after stacked discounts and an optional coupon, with every step shown.
Formula & worked example
Formula: Price after each step = price × (1 − discount ÷ 100); a coupon is subtracted as a fixed amount. Total discount = (original − final) ÷ original.
Example: 120 with 25% then 10% off = 81 (32.5% off, not 35%). A 5 voucher applied last makes it 76.
Method & source: Successive percentage-change method (multiplying the remaining fractions). See how we test our calculators.
Next step: try reverse percentage or percentage change.
Stacked Discounts, Explained
A sale price calculator shows what an item really costs after one or more discounts. Shops often combine a percentage off with a further reduction or a voucher, and the final price is not what simply adding the percentages suggests.
This sale price calculator with stacked discounts applies up to three percentage discounts one after another, then an optional coupon, and shows the price after every step and your true total saving.
Applying Several Discounts in Order
Enter the original price and up to three percentage discounts. Add a fixed coupon if you have one.
- Stacked percentages: each discount is taken from the price left after the previous one.
- Coupon order: choose whether the coupon is applied before or after the percentages.
- Step table: see the amount taken off and the price after each step.
- Real discount: the total percentage you actually save compared with the original price.
- Reality check: a note shows what adding the percentages together would wrongly suggest.
Prices never go below zero, and a 100% discount simply brings the price to nothing.
Why Checking Stacked Discounts Matters
A headline such as “20% off, plus an extra 10%” sounds like 30%, but the maths says otherwise.
- See the real price before you decide to buy.
- Compare two offers with different combinations of discounts.
- Understand why two 10% discounts are not a 20% discount.
- Check whether a voucher is worth more before or after the sale percentage.
- Avoid being misled by adding percentages together.
A few seconds with a discount calculator turns a confusing promotion into one clear number.
Worked walkthrough: a promotion with a voucher
A jacket costs 120 with 25% off, plus an extra 10% for members and a 5 voucher. The first discount takes off 30, leaving 90. The second takes 9 off that, leaving 81. The voucher applied last brings it to 76, a total saving of 44 or about 36.7%. Adding 25% and 10% would suggest 35%, but the percentages alone save 32.5%. If the voucher is taken off before the percentages, the price becomes 77.63 instead, so applying it last is 1.63 cheaper in this case.
Practical tips for Discount calculations
- Do not add percentages together. Two discounts of 20% and 10% give 28% off, not 30%.
- Read the small print about the order of discounts: some shops apply a voucher first, which can change the final price.
- To compare deals, convert everything to a final price rather than comparing headline percentages.
- For a “buy one, get one half price” offer, enter the total price of both items and the effective discount to check the saving.
- Use the Reverse Percentage Calculator if you know a sale price and need to find what the item cost before the discount.
How stacked discounts combine
Each discount applies to the price left after the previous one, so the percentages multiply rather than add. Two discounts of 20% and 10% leave 0.80 × 0.90 = 72% of the price, a total saving of 28%, not 30%. The bigger the discounts, the bigger the gap between adding and multiplying.
| Discounts stacked | Real total discount |
|---|---|
| 10% then 10% | 19% |
| 20% then 10% | 28% |
| 25% then 10% | 32.5% |
| 30% then 20% | 44% |
| 50% then 50% | 75% |
Three discount formulas, with examples
- Sale price = original price × (1 − discount ÷ 100).
- Discount amount = original price × discount ÷ 100.
- Original price = sale price ÷ (1 − discount ÷ 100).
| Question | Working | Answer |
|---|---|---|
| 20% off 85 | 85 × 0.80 | 68 (17 saved) |
| 35% off 240 | 240 × 0.65 | 156 (84 saved) |
| Original price of 63 after 30% off | 63 ÷ 0.70 | 90 |
| 20% then 10% off 100 | 100 × 0.80 × 0.90 | 72 (28% in total, not 30%) |
This calculator works forwards from the original price, so use it for the first, second and fourth rows; the third formula is what the reverse percentage calculator does. If a shelf price also includes sales tax or VAT, the VAT calculator separates it out, and sellers can check what a discount leaves them with in the profit margin calculator.
Percentage coupon or money-off voucher?
A fixed voucher and a percentage discount do not commute. On a price of 100 with 20% off and a 10 voucher, taking the percentage first gives 80 − 10 = 70, whereas taking the voucher first gives 90 × 0.80 = 72. The calculator subtracts the voucher after the percentage steps, which is the order most retailers use, so check the small print for yours.
Percentage discounts and percentage taxes, by contrast, can be applied in either order: a 20% discount and 20% VAT give the same final price whichever comes first.
Multi-buy offers as percentages
Promotions can be converted into an equivalent discount to compare them fairly. “3 for 2” means paying for two of every three items, a saving of 33.3%. “Buy one, get one half price” means paying 1.5 prices for two items, a saving of 25% on each pair. To model one, enter the equivalent percentage as a discount step.
Measuring the real saving
The saving is the original price minus the final price, and the effective discount is that saving as a share of the original. The step table shows the price after every step, which makes it easy to see which offer does the most work. If you only know the sale price, the reverse percentage calculator recovers the original, and the percentage change calculator compares two prices directly.
Frequently Asked Questions (FAQs)
Multiply the original price by (1 − discount ÷ 100). A 20% discount on 100 gives 100 × 0.80 = 80.
Use the Reverse Percentage Calculator, which divides the sale price by (1 − discount ÷ 100).
No. A 100% discount makes the item free, and the calculator limits each percentage to between 0% and 100%.
No. The second discount applies to the already reduced price, so £100 becomes £80 and then £72, a total saving of 28%, not 30%. The calculator applies stacked discounts in order for this reason.
Multiply the price by 0.8, which is 100% minus 20%. Taking 20% off 85 gives 85 × 0.8 = 68, a saving of 17. Or work out 20% of the price first (85 × 0.2 = 17) and subtract it. In the calculator, enter 85 as the original price and 20 as the first discount, and the step table shows the amount taken off.
Enter the coupon as a money amount in the coupon box, and choose whether it comes off before or after the percentage discounts. The order matters: with 20% off 100 and a 10 coupon, taking the coupon after the discount gives 70, but before it gives 72. The coupon box takes a fixed amount; for a percentage coupon, enter it as another discount instead.
The result shows the final price and the amount you save, with every step listed.
Guides that use this calculator
- Black Friday 2026: How Stacked Discounts Really Add Up – Black Friday is Friday 27 November 2026. Two discounts of 30% and 20% do not make 50% off: on £200 you pay £112, a 44% saving. Worked examples and a table.