Discount
calculator.
Find the sale price and how much you save, stack an extra discount correctly, add sales tax, or work backwards from a sale price to the original price or the percentage off.
What you really
pay and save.
- A percentage discount is taken from the original price: sale = price × (1 − discount ÷ 100).
- An extra discount applies to the already-reduced price, so 20% + 10% is 28% off, not 30%.
- Sales tax is added after the discount, on the price you actually pay. Leave tax at 0 where prices include VAT or GST.
- Amounts are calculated exactly and shown rounded to the cent. A store that rounds each step may differ by a cent.
How do you calculate a discount?
Multiply the original price by the discount percentage divided by 100 to get the amount saved, then subtract it. For a $120 item at 20% off, you save 120 × 0.20 = $24 and pay $96. A quicker way is to multiply by what remains: 120 × 0.80 = $96.
savings = price × discount ÷ 100
sale price = price × (1 − discount ÷ 100)How do stacked discounts work?
“An extra 10% off sale prices” applies to the price after the first discount, not to the original. So 25% off followed by 10% off leaves 0.75 × 0.90 = 0.675 of the price, which is 32.5% off in total, not 35%. The order does not matter: 10% then 25% gives the same result. The calculator shows the true combined percentage.
sale = price × (1 − d₁ ÷ 100) × (1 − d₂ ÷ 100)How do you find the original price?
If you know the sale price and the percentage off, divide the sale price by what remains. A jacket that costs $63.75 after 15% off was originally 63.75 ÷ 0.85 = $75. Adding 15% to $63.75 gives $73.31, which is wrong, because the 15% was taken from the larger original price.
original = sale ÷ (1 − discount ÷ 100)
discount % = (original − sale) ÷ original × 100Is sales tax charged before or after a discount?
In U.S. states with sales tax, a store's own discount usually reduces the taxable price, so tax is charged on the discounted amount. That is what this calculator does. Rules can differ for other price reductions. In New York, for example, the state tax department explains that a store coupon reduces the taxable receipt but a manufacturer's coupon generally does not. Where prices already include VAT or GST, leave the tax field at 0.
Worked examples.
A simple sale
A $120 item is 20% off.
You pay $96.00 and save $24.00.
Load this exampleAn extra discount plus tax
An $80 item is 25% off, with an extra 10% off at the register and 8.875% sales tax.
$58.79 with tax ($54.00 before tax). The combined discount is 32.5%, not 35%.
Load this exampleA fixed amount off several items
$10 off each of 3 items priced at $45.
$105.00 in total, saving $30.00 (22.2% off).
Load this exampleFind the original price
A jacket costs $63.75 after 15% off. What was the original price?
$75.00 (you saved $11.25).
Load this exampleWhat percentage off is it?
A price drops from $249.99 to $179.99.
28.00% off (exactly 28.0011%), saving $70.00.
Load this exampleWhat this calculator
does not do.
- It does not know your local tax rate or which items are taxable. Enter the rate yourself.
- It does not model offers like “buy one, get one half price”. Work those out per item, or as an amount off.
- It shows the effect of discounts. It cannot tell you whether the original price was a genuine one.
Common questions.
How do I calculate 30% off?
Multiply the price by 0.70. For example $50 × 0.70 = $35, saving $15.
Is 20% off plus 20% off the same as 40% off?
No. It is 36% off, because the second 20% is taken from a price that has already been reduced: 0.8 × 0.8 = 0.64.
How do I reverse a discount?
Divide the sale price by (1 − discount ÷ 100). $80 after 20% off was 80 ÷ 0.8 = $100.
Can I calculate a price increase?
Use the percentage calculator, which handles increases, decreases and percentage change.
- New York State Department of Taxation and Finance — Tax Bulletin ST-140, Coupons and Food Stamps — an example of how store and manufacturer discounts are taxed differently
Standard percentage arithmetic, calculated in your browser with full precision and rounded only for display. Our test suite checks independently computed vectors for single, stacked and fixed discounts, tax, quantity, reverse and find-percentage modes, plus property tests (stacking is order-independent; reversing a discount recovers the original price).