Discount Calculator
Work out the sale price and exact savings for any deal: a percentage off, a fixed amount off, two stacked discounts, or group offers like 2 for 1 and 3 for 2. Add a quantity and an optional sales tax, or reverse solve to find the original price or the percent off you are really getting.
Formula
Worked example
An $80 item at 25% off saves 80 × 0.25 = $20, so the sale price is $60. Stacking 20% then 10% gives 80 × 0.80 × 0.90 = $57.60, an effective 28% off. A 3 for 2 deal on $80 items is 80 × 2/3 = $53.33 each, about 33.3% off.
How the Discount Calculator Works
For a percentage off, the calculator multiplies the original price by the discount rate to find the saving, then subtracts it from the price to give the sale price. A fixed amount off simply subtracts the coupon value. Stacked (double) discounts apply one rate after the other, so they multiply rather than add: 20% then 10% off leaves you paying 0.80 times 0.90, which is 72% of the price, an effective 28% off, not 30%. Group deals such as 2 for 1, 3 for 2 and 4 for 3 spread the cost of the paid items across the whole bundle, giving effective discounts of 50%, 33.3% and 25% per unit. Whatever the deal, the tool reports the sale price, the money saved and the effective percentage off so you can compare offers fairly.
Quantity, sales tax and the total
Set a quantity to price a multi-unit purchase, the per-unit sale price is multiplied by the count to give a subtotal. Turn on sales tax to add a percentage on top of the discounted subtotal, which is how most US states and many other jurisdictions charge tax: on the price you actually pay after the discount, not the original ticket price. The grand total then shows the all-in amount due at the register. Leaving tax off shows the pre-tax sale price, useful where tax is already included or quoted separately.
Reverse solving a deal
Two reverse modes turn the math around. Choose "Find original price" when you know the sale price and the percentage off and want the pre-sale ticket price: the calculator divides the sale price by one minus the rate. Choose "Find discount percent" when you know both the original and the final price and want to see the true percentage off you are getting, which is the saving divided by the original price. These modes are handy for spotting fake "was" prices and for checking whether a headline discount matches the actual reduction at the till.
Limitations and good practice
Percentage discounts run from 0% to 100%; 100% off gives a sale price of zero, which is correct but rarely a real transaction. For buy-one-get-one-free, the effective discount is 50% per unit, so use the 2 for 1 mode rather than entering 100%. Currency conversion is not built in, convert a foreign price to your own currency first. The tax figure uses a single flat rate, so check your local combined state and local rate, and remember that some items are tax exempt. Stacked-discount order does not change the final price because multiplication commutes, but it can change rounding by a cent on very large baskets.
Effective discount of common deals
| Deal | You pay | Effective discount |
|---|---|---|
| 25% off | 75% of price | 25% |
| Buy one get one free (2 for 1) | half per unit | 50% |
| 3 for 2 | two thirds per unit | 33.3% |
| 4 for 3 | three quarters per unit | 25% |
| 20% then 10% (stacked) | 72% of price | 28% |
| 50% then 50% (stacked) | 25% of price | 75% |
How everyday offers compare once the math is worked out per unit.
Frequently asked questions
How do I calculate the price after a percentage discount?
Multiply the original price by the discount percentage expressed as a decimal (for example 25% becomes 0.25) to find the savings, then subtract that amount from the original price. An $80 item at 25% off saves you $20, giving a final price of $60. This calculator performs both steps automatically and also shows the effective percent off.
How do two stacked discounts (a double discount) combine?
Stacked discounts multiply, they do not add. Taking 20% off and then a further 10% off leaves you paying 0.80 times 0.90, which is 0.72, so you pay 72% of the price for an effective 28% discount, not 30%. Select the double discount mode and the calculator applies the second rate to the already reduced price and reports the true combined percentage.
What discount is a 2 for 1 or 3 for 2 deal really worth?
A 2 for 1 deal charges for one item across two, an effective 50% off per unit. A 3 for 2 charges for two across three, about 33.3% off each, and a 4 for 3 is 25% off each. Pick the group deal from the dropdown and the calculator works out the bundle price, the per-unit price and the effective percentage so you can compare it against a straight percent off.
Is the discount applied before or after sales tax?
In most US states and many other jurisdictions, sales tax is charged on the post-discount sale price, not the original price, so a discount lowers the tax you owe as well. Turn on the sales tax option to add your local rate to the discounted subtotal and see the grand total due at checkout. Leave it off to see the pre-tax sale price.