How to use the discount calculator
- Pick a tab. Sale price is for a known percent off, Find % off is for when you know both prices, and Two discounts is for an extra percent off an already reduced price.
- Type the Original price and the Discount (% off). Dollar signs, commas and percent signs are fine.
- Add a Sales tax (%) rate if you want the checkout total.
- Read You save and Sale price, plus Sales tax and Total with tax when a rate is entered. Results update as you type.
The formulas
- Savings = Original price × Discount % ÷ 100, and Sale price = Original price − Savings.
- Percent off = (Original price − Sale price) ÷ Original price × 100.
- Two discounts: Final price = Original price × (1 − first % ÷ 100) × (1 − extra % ÷ 100). The effective discount is 1 minus that product.
- Sales tax = Sale price × tax rate ÷ 100, charged on the discounted price.
Money is rounded to the cent at each step, like a register, so savings plus sale price always equals the original price.
Worked example with the default numbers
25% off $120.00 saves 120 × 25 ÷ 100 = $30.00, so the sale price is $90.00. In Find % off, a price cut from $180.00 to $126.00 saves $54.00, and 54 ÷ 180 = 30% off. In Two discounts, 20% off $200.00 leaves $160.00, and a further 10% off leaves $144.00. You save $56.00, an effective 28% off rather than the 30% the two numbers seem to add up to.
Limits and edge cases
- Discounts must be between 0% and 100%. If the sale price is higher than the original, the tool tells you it is a price increase instead of showing a negative discount.
- Tax is applied after the discount, which is how store discounts and store coupons are usually taxed. Manufacturer coupons can differ: in states such as New York, tax is charged on the price before the coupon because the store is reimbursed.
- For a fixed dollar deal such as $15 off, enter the original and the reduced price in Find % off to see the equivalent percent. For other percent questions, use the percentage calculator, and for tax on several items or a price with tax already included, use the sales tax calculator. Sellers pricing from cost can check the markup calculator to see how a markdown eats into margin.
Discount questions people ask
How do I calculate 20% off a price?
Multiply the price by 0.20 to get the savings and subtract it, or multiply the price by 0.80 in one step. For example, 20% off $50 is $50 × 0.80 = $40, a saving of $10.
Is 20% off plus an extra 10% off the same as 30% off?
No. The extra 10% comes off the already reduced price, so you pay 0.80 × 0.90 = 72% of the original, which is 28% off. On a $200 item that is $144 instead of $140.
Does the order of two discounts matter?
Not when both are percentages, because the multipliers give the same product in either order. It does matter when one is a fixed amount: on a $100 item, 20% off and then $10 off costs $70, but $10 off first and then 20% off costs $72.
Is sales tax charged before or after a discount?
For a store sale or store coupon, tax is normally charged on the reduced price. For a manufacturer coupon, many states, including New York, charge tax on the full price because the manufacturer reimburses the store.
What percent off is buy one, get one 50% off?
When both items cost the same, you pay 1.5 times the single price for two items, which is 25% off the pair. Buy one, get one free works out to 50% off the pair.
Sources: New York State Department of Taxation and Finance, Tax Bulletin ST-140, Sales Tax Treatment of Coupons (store versus manufacturer coupons). Checkout totals can differ because of shipping, fees and store rounding rules.