Free tool
Discount Calculator That Stacks Offers and Compares Deals
Four modes cover the questions that come up around a sale: the price after a discount, the price before one, the percent off between two prices, and which of up to three deals is cheapest. Each answer comes with numbered steps so you can see how it was reached.
Deal A
Deal B
Deal C
Plain maths, not financial or legal advice.
Prices are worked out in your browser and never sent anywhere. Your last numbers are kept on your own device, and the share link puts them in the part of the address after the hash sign.
Choose the mode that fits the tag in front of you
A price tag can leave you with different gaps. You may know the original price and the offer, and want what you will pay. You may see only a sale price and a percent, and want to know what the item used to cost. Or you may have two prices and want the discount between them. The mode menu has one entry for each, and a fourth for choosing between competing offers.
| Mode | Fill in | Result |
|---|---|---|
| Price after a discount | Price, one or two discounts, optional tax | Sale price, amount saved, total |
| Original price | Sale price and percent off | The price before the discount |
| Percent off | Original and sale price | The percent saved |
| Which deal is better | Item price, quantity, up to three deals | The cheapest deal and a table |
Two discounts in a row
The first mode takes a second discount, and each one can be a percent off or a flat amount off. The steps show them applied one after the other. Two percent discounts multiply, so 20% and then 10% leaves 72% of the price, which is 28% off in all and not 30%. The result cards show that single combined percent.
If you mix one percent and one fixed amount, the order changes the answer. The tool works out the price both ways and tells you the difference, which is useful when a shop code and a coupon can be used together and you do not know which is taken first.
- A discount bigger than the price stops the price at zero.
- A percent above 100 is refused with a message.
- Prices are shown to the cent, and the maths behind them is exact until that last step.
Adding sales tax without guessing a rate
There is a tax box, and it starts empty on purpose. The page does not assume any rate, so you type the one that applies to you. A second menu sets whether tax is worked out on the sale price or on the original price, because shops and regions differ. With a rate entered, the cards add a tax amount and a total to pay.
A shop that rounds at every step can land a cent away from this result, as the note under the answer says. For anything with legal or accounting weight, check against the receipt, as this is plain maths and not advice.
Comparing deals that are worded differently
Offers rarely look alike. One shop gives 25% off, another takes a fixed amount off the order, and a third sells three for the price of two. The compare mode turns all of them into a cost for the number of items you want.
- Percent off reduces the whole order by that share.
- Amount off the order takes a flat sum from the total.
- Buy some, get some free gives the free items in complete groups only, so buying four on a buy 2 get 1 deal still only earns one free item.
- Percent off every second item discounts every second unit by the share you enter.
A table under the answer repeats the comparison for one to eight items. The cheapest deal can change as the basket grows, so it is worth a glance before you decide.
If you run the store
Seeing how stacked codes behave helps you set the rules for your own shop. A shop owner who lets a code and a sale combine should know the real combined percent first. If you are setting up a store and want the sales and checkout rules planned with it, our Shopify development page shows how we build around them.
Frequently asked questions
How do I calculate a price after a discount?
Multiply the price by one minus the discount as a decimal. For 20% off 100, that is 100 times 0.8, giving 80.
Is 20% off and then 10% off the same as 30% off?
No. The second discount applies to the reduced price, so the total is 28% off. The tool shows that combined figure.
How do I find the original price from a sale price?
Use the original price mode. It divides the sale price by what remains after the discount, so a sale price of 60 after 25% off gives 80.
Does the order of discounts matter?
For two percent discounts it does not. If one is a percent and one is a flat amount, it does, and the tool shows both results.
How does buy 2 get 1 free count?
Each full group of three has one free item. Four items still only include one free, and six include two.
Which tax rate does it use?
None. You type your own rate, and you choose whether it applies to the sale price or the original price.
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