Discount Calculator

This tool takes one percentage off one price, and that's deliberately all it does. Knowing its limits is more useful than knowing the formula, so most of this page is about those.

Straightforward case first

A 249.00 item at 35% off:

• You save: 87.15
• Sale price: 161.85

Saving    = price × discount ÷ 100
Sale price = price − saving

The discount input is bounded at 0 to 100. Anything outside that range is rejected, because a 120% discount would mean a negative price and no shop can do that.

Stacked discounts multiply, they don't add

It's the usual reason people get a till receipt they weren't expecting.

Take 100.00. Apply 20% off and you have 80.00. Apply a further 10% to that and you have 72.00. That's a total reduction of 28%, not 30%, because the second percentage is taken from the already-reduced figure. Each discount after the first is worth less than its face value.

There's no second-discount field on this page. To model a stack, run the tool twice: take the sale price from the first pass and use it as the original price in the second. The order doesn't matter, since 10% then 20% also lands on 72.00.

Percent off versus the price you pay

Two ways of stating the same offer:

Retail marketing quotes the first column because it's the bigger number. The second column is easier when you're comparing two offers. An item at 40% off in one shop and 30% off in another can only be compared if the list prices match, and they often don't. Look at the final prices you'd actually pay.

What this does not include

Tax. The calculation is entirely pre-tax. Where tax is added at the register, it's levied on the discounted price, so the saving is slightly larger than shown. Where tax is already inside the shelf price, the discount reduces both the net and the tax.

Shipping. A free-shipping threshold can make a smaller discount the better deal.

Coupon rules. Stacking is often prohibited outright, and a percentage coupon frequently excludes sale items, gift cards and specific brands.

The reference price. A percentage means only as much as the price it's taken from. An "up to 70% off" banner typically applies to a handful of lines, and a discount from an inflated list price doesn't save you anything. This tool takes the original price at face value. Whether that price was ever real is for you to judge.

Elsewhere on the site

To check whether a proposed discount still leaves a workable margin, use the profit margin calculator. To add tax to the discounted figure afterwards, use the sales tax calculator or the VAT calculator. For percentage arithmetic in other directions, use the percentage calculator.