Discount Calculator

How to use this calculator

1. Choose what you know: an original price and a discount, an original price and a sale price, or a sale price and a discount.
2. Enter your prices. In the first mode, choose a percentage or a fixed amount off, and use the quick percentage buttons if one matches the discount shown by the seller.
3. Open Add more discounts to stack up to two further percentage discounts and one more fixed amount off — each is applied to the already-reduced price, in order.
4. Enter a quantity if you are buying more than one, to see the subtotal for all of them.
5. Open Add tax after discount if you want a tax percentage or amount added to the sale price, applied after every discount.
6. Read the sale price, savings and effective discount below the form, along with the full step-by-step breakdown.

What do I need to enter?

• What do you know? — picks the calculation: original price and discount, original price and sale price, or sale price and discount. Only the fields for that mode count.
• Original price — the price before any discount, 0 or more. It must be greater than 0 when you also enter a sale price.
• First discount — Percentage off (0 to 100%, with quick buttons from 10% to 50%) or Fixed amount off (0 or more, capped at the price).
• Sale price before tax — what you pay after the discount, 0 or more.
• Discount percentage — used when you know the sale price. It must be 0 or more and below 100%, since an original price cannot be found from a full discount.
• Add more discounts — optional second and third percentage discounts and an extra fixed amount off. Leave them blank to skip them.
• Quantity — whole units from 1 to 10,000. It multiplies the per-unit result.
• Add tax after discount — No tax, a Tax percentage (0 to 100%) or a Tax amount, applied after every discount.

What do the results show?

• Sale price — the price after all discounts, before tax. With a quantity above 1 it also shows the per-unit price.
• You save and Effective discount — the total amount taken off, and that amount as a percentage of the original price.
• Percentage off — in the original and sale price mode, the discount implied by your two prices. It reads Price increase if the sale price is higher.
• Estimated original price — in the sale price and discount mode, the price before the discount.
• Final price with tax — shown when tax is entered; the total after the discount and tax.
• Price breakdown — a table of each step from original price to final price.

How is a discount calculated?

A percentage discount is the original price multiplied by the discount rate; the sale price is what remains after that amount is taken off.

For example, 25% off an £80 item is a discount of £80 × 25 ÷ 100 = £20, giving a sale price of £80 − £20 = £60. The same maths works in reverse: a $72 sale price after 20% off implies an original price of $72 ÷ (1 − 0.20) = $90.

How do stacked discounts work?

Each extra percentage discount is calculated on the price that is already reduced, not on the original price, and not simply added to the first percentage. Two 20% discounts on $100 give $100 × (1 − 0.20) × (1 − 0.20) = $64 — a 36% total discount, not 40% off. A fixed amount off is always applied last in this calculator, after every percentage discount, and is capped at whatever price remains so the sale price is never negative.

Working out a single discount by hand? The Percentage Calculator covers the plain percentage-of-a-number maths behind the first step here.

Assumptions and what this calculator does not do

• Prices are treated as pre-tax, pre-shipping and pre-fee unless you enter a tax figure.
• Discounts are applied in a fixed, sequential order — never simply added together.
• A fixed discount is capped at the current price and never produces a negative sale price.
• Tax, when entered, is a manual percentage or amount applied after every discount, not a looked-up rate.
• Every unit is assumed to be discounted identically; quantity multiplies the per-unit result.
• Coupon codes, multi-buy offers, shipping, delivery fees, retailer rules and currency conversion are not included.

Pricing a markup instead of a discount? See the Markup Calculator. Splitting a bill that already includes a discount, service charge or tip? See the Tip Calculator.

Frequently asked questions