Discount Calculator
CalculatorsThe sale price, what you save, and what two discounts really add up to — in any currency.
You pay
72.00
You save 28.00 — 28% off in total
price × (1 − 20%) × (1 − 10%)
- 20% off
- 80.00
- saves 20.00
- 100.00 × 0.8
- Then 10% off
- 72.00
- saves 8.00
- 80.00 × 0.9
20% + 10% is 28% off, not 30%. Each discount is taken from a price the one before it has already reduced.
How this is calculated
One discount final = price × (1 − d) Stacked discounts final = price × (1 − d₁) × (1 − d₂) Original price original = sale ÷ (1 − d) Discount given d = (original − sale) ÷ original d is the discount as a fraction: 20% is 0.20. Stacked discounts multiply. They never add.
How it works
A discount takes a share of the price away, so what you pay is the share that is left: 25% off leaves 75%, and 80 × 0.75 is 60. That part is simple. The places people go wrong are the other three things this calculator does.
Stacked discounts multiply rather than add. "20% off, plus an extra 10% at the till" is not 30% off. The first discount brings 100 down to 80, and the extra 10% is taken from that 80, not from the original 100, so you pay 72 — 28% off in total. The more discounts are stacked, and the larger they are, the wider the gap between the sum you might expect and the discount you actually get. Two 50% discounts are 75% off, not free.
Because percentage discounts multiply, their order does not matter: 40% then 15% ends at exactly the same price as 15% then 40%. That stops being true the moment a fixed amount is involved. A 10-off voucher taken off before a 20% discount is worth only 8, because the 20% is then worked out on a price 10 lower; taken off after the discount, it is worth the full 10.
Working backwards from a sale price is the other common slip. If something costs 72 after 28% off, adding 28% back on gives 92.16, not the original. The discount was a share of the original price, so the sale price has to be divided by the share that was left — 72 ÷ 0.72 is 100.
Worked example
A jacket marked 80, 25% off, with an extra 10% off at checkout
- First discount 80 × (1 − 0.25) = 60.00
- Extra discount 60 × (1 − 0.10) = 54.00
- You save 80 − 54 = 26.00
- Effective discount 26 ÷ 80 = 32.5%
- Not 35%: the extra 10% came off 60, not 80.
You pay 54.00 — 32.5% off in total, not the 35% the two figures suggest
How to use it
- Choose what you want to know: the price after a discount, the original price from a sale price, or the discount a price change represents.
- Enter the prices in any currency — the arithmetic is the same whatever it is.
- For a stacked discount, add a second or third one. They are applied in order, and the result shows the price after each.
- Read the effective discount under the total: it is the single discount the whole stack amounts to.
What this tool does not do
- Percentage discounts only. Fixed-amount vouchers, such as 10 off, are not modelled — and unlike percentages, where they fall in the order changes the total.
- Sales tax is not added. Where tax is added at the till, whether it is charged on the price before or after a discount depends on where you are and on who is giving the discount, so check the receipt rather than assuming.
- Results are exact and shown to two decimal places. A shop that rounds each step to the cent can end up a cent away from the figure here.
- No currency is assumed. Enter prices in whatever currency you are paying in.
- Multi-buy offers such as buy one, get one half price are not calculated directly. Treat them as a discount on the total of the items together.
Frequently asked questions
Is 20% off plus an extra 10% off the same as 30% off?
No. It is 28% off. The extra 10% is taken from the price after the first discount, not from the original, so on 100 you pay 80 after the first discount and 72 after the second. The gap grows with bigger discounts: 50% off twice is 75% off, not 100%.
Does the order of two percentage discounts matter?
Not for the final price. Percentage discounts multiply, and multiplication gives the same answer in any order: 40% then 15% and 15% then 40% both end at 51% of the original. Order does matter as soon as one of them is a fixed amount off, such as a voucher.
How do I find the original price from the sale price?
Divide the sale price by what was left after the discount. If something is 72 after 28% off, 72% was left, so the original was 72 ÷ 0.72 = 100. Adding 28% on to 72 gives 92.16, which is wrong, because the discount was a share of the original rather than of the sale price.
How much is 30% off 59.99?
59.99 × 0.70 = 41.99, to the cent, saving 18.00. The quick way to do any of these in your head is to work out what is left rather than what is taken: 30% off means paying 70%.
Why is my receipt a cent different from this?
Rounding. This calculator keeps every step exact and rounds only the answer, while a till usually rounds each discounted line to the cent before applying the next discount or adding them up. Over a few steps that can move the total by a cent either way.
Is a discount the same as a markdown or a percentage decrease?
The arithmetic is the same: both measure how far a price fell as a share of where it started. Use the Discount given mode with the before and after prices. If the second price is higher, the result says it is a price rise instead.
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Last updated 13 September 2026.