How do I calculate a percentage discount?

Multiply the original price by the discount percentage to get the amount off, then subtract it from the price. For 20% off $100: 100 × 0.20 = $20 off, so the sale price is $80. This tool does it for you as you type.

How do stacked discounts work?

Stacked discounts apply one after another, not added together. 20% off then 10% off means the second discount comes off the already-reduced price: $100 → $80 → $72. That is an effective discount of 28%, which this calculator shows so you do not over-promise.

What is the margin after a discount?

Margin is the profit left as a share of the sale price. Enter your cost per item and the calculator subtracts it from the sale price to show the profit, and the margin percentage. It also warns you if the discount sells below your cost.

Is this discount calculator free?

Yes — it is free, needs no sign-up, and runs entirely in your browser.

Free tool · No sign-up

Discount Calculator

Enter a price and a percent off to see the sale price and how much you save. Stack a second discount, and add your cost to check the margin left at the sale price. Everything runs in your browser.

Original price ($)Discount (%)Stack a second discount (%) — optionalYour cost per item ($) — for margin, optional

Sale price$80.00

You save$20.00

Effective discount20%

How to calculate a discount

01
Enter the price
Type the original price of the product before any discount.
02
Add the percent off
Enter the discount percentage — and a second one if you are stacking offers. The sale price updates as you type.
03
Check the margin
Add your cost per item to see the profit and margin left at the sale price, so a promotion never quietly sells below cost.

Working out a sale price and what it costs you

A discount calculator answers two questions a percent-off sale raises. The first is simple arithmetic: what is the sale price, and how much does the shopper save? Enter the original price and the discount, and this tool gives you the sale price, the amount saved, and the true effective discount — which matters the moment you stack two offers, because 20% off then another 10% off is 28% off, not 30%.

The second question is the one that decides whether a promotion is worth running: what does the discount do to your margin? Add your cost per item and the calculator shows the profit left at the sale price and the margin percentage. If a discount drops the price below your cost, it says so, because the fastest way to lose money on a sale is to not do this sum first.

Once you know the number that works, the next step is putting it in front of shoppers. That is what OfferBanner does: it shows the offer as a banner on your site, creates the real discount code in your own Stripe account, and takes the campaign down on the date it ends.