Discount Calculator
✦ Finance & MoneyUse this discount calculator to find the sale price and what you save from a percent off or a dollar discount, with sales tax on the discounted price. It also works as a double discount calculator — 20% then 10% off is 28%, not 30% — and works backwards from a sale price to the original price or the percent off.
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- ✓ Nothing you type is stored
- ✓ No sign-up required
- ✓ Formula and sources shown
The formula
Percent off, stacked discounts and sales tax after the discount
\text{Sale price} = P \times \left(1 - \frac{d}{100}\right) \qquad \text{Two discounts: } P \times \left(1 - \frac{d_1}{100}\right)\left(1 - \frac{d_2}{100}\right) \\[4pt]
\text{Combined \%} = d_1 + d_2 - \frac{d_1 d_2}{100} \qquad \text{Total} = \text{Sale price} \times \left(1 + \frac{t}{100}\right) \qquad \text{Original} = \frac{\text{Sale price}}{1 - d/100}Each percentage applies to the price left after the step before it, so stacked discounts compound rather than add. A dollar coupon gives a different price before or after the percentages; the page shows both. Sales tax is charged on the price after store discounts and store coupons; a manufacturer coupon reimbursed by a third party can be taxed on the price before it. Money is shown to the cent.
Calculating it by hand
- On the Discount tab, enter the original price, choose percent off or dollars off, and enter the discount.
- Enter your sales tax rate; tax is worked out on the price after the discount.
- For two discounts and a coupon, open Stacked discounts and enter both percentages, the coupon and whether it comes off before or after them.
- To work backwards, open Original price and enter the sale price and the percent off (or both prices to find the percent off).
- Under Advanced, enter a quantity to see the total for several items.
- Read the sale price, the saving and the total with tax; the chart shows each step from the original price to what you pay.
Worked examples
25% off a $150 item with 7% sales tax (the page defaults)
Discount tab: original price $150.00, percent off, discount 25%, sales tax rate 7%.Saving = $150.00 × 0.25 = $37.50; sale price = $150.00 − $37.50 = $112.50.Sales tax = $112.50 × 0.07 = $7.875, shown as $7.88.Total = $112.50 + $7.88 = $120.38.
Sale price $112.50 · you save $37.50 · total with tax $120.38
Two stacked discounts on a $200 purchase
Stacked discounts tab: original price $200.00, first discount 20%, second discount 15%, coupon $0, sales tax 0%.After 20% off: $200.00 × 0.80 = $160.00.After a further 15% off: $160.00 × 0.85 = $136.00.Saving = $64.00, which is 32% of $200.00 — not 35%.
Sale price $136.00 · you save $64.00 · 32% off in all
Working back from a sale price
Original price tab: work out the original price; sale price $84.00; percent off 30%.Original price = $84.00 ÷ (1 − 0.30) = $84.00 ÷ 0.70 = $120.00.Amount off = $120.00 − $84.00 = $36.00.
Original price $120.00 · $36.00 off
Methodology
How discounts are calculated
A discount is a percentage of whatever price is left at that moment. Two discounts in a row therefore never add up to their sum, and a coupon is worth more taken off before a percentage than after it.
Read sources and limitsWhat does a discount calculator do?
A discount calculator takes a percentage or a dollar amount off an original price and shows the sale price, the amount you save and, with a sales tax rate, the total you pay. This one also stacks two percentage discounts and a coupon in the order you choose.
It works backwards too, from a sale price to the original price or the percent off. At the page defaults a $150.00 item at 25% off costs $150.00 × 0.75 = $112.50, a saving of $37.50. With 7% sales tax on the discounted price the tax is $7.88 and you pay $120.38 — $2.63 less tax than on the full price.
How do you calculate a percent off?
Multiply the original price by the discount as a decimal to get the saving, and subtract it: 30% off $50 saves $50 × 0.30 = $15.00 and leaves $35.00. Or multiply by what is left: $50 × 0.70 = $35.00.
In your head, find 10% by moving the decimal point one place left and scale it — 10% of $60 is $6, so 40% off is $24 off and $36 to pay.
A dollar discount is simpler: $20 off $150 is $130, which is 13.33% off. The Discount tab takes either and shows the other as the effective percentage.
Is 20% off plus an extra 10% off the same as 30% off?
No. The second discount applies to the price after the first, so it takes less off. $100 at 20% off is $80; an extra 10% off $80 is $8, leaving $72 — a 28% discount, not 30%. The combined rate is always d₁ + d₂ − d₁ × d₂ ÷ 100.
The order of the two percentages does not matter: 10% off and then 20% off also leaves $72. At the stacked-tab defaults a $200 item at 20% then 15% off is $200 × 0.80 × 0.85 = $136.00, which is 32% off, not 35%.
Does it matter whether a coupon comes before or after the percent off?
Yes, for a dollar coupon. Taken after the percentages, the coupon comes off in full; taken before, the percentages then shrink what is left. At the defaults — $200, 20% and 15% off, and a $10 coupon — the coupon last gives $126.00 and the coupon first gives $129.20.
Coupon last: $200 × 0.80 × 0.85 = $136.00, less $10 = $126.00. Coupon first: ($200 − $10) × 0.80 × 0.85 = $129.20, because the percentages also shrink the part the coupon already removed. The promotion's terms decide the order; the page shows both so you can check the receipt.
Is sales tax charged before or after a discount?
After a store discount. In the states that follow the Streamlined Sales and Use Tax Agreement, the taxable "sales price" excludes discounts and coupons the seller gives that no third party reimburses — Rhode Island General Laws § 44-18-12 is one example of the definition in state law.
A manufacturer's coupon is different: the store is reimbursed, so the coupon's value is usually still part of the taxable price, as the Minnesota Department of Revenue's Revenue Notice 05-06 shows with a $1.00 coupon. Rules vary by state, and this page treats every discount you enter as a store discount.
With a 7% rate, tax on the $112.50 sale price is $7.88, against $10.50 on the full $150.00.
How do you find the original price from a sale price?
Divide the sale price by what is left after the discount: $84.00 after 30% off was $84.00 ÷ 0.70 = $120.00, so the discount took $36.00 off. To find the percent off from two prices, divide the difference by the original: from $120.00 to $84.00 is $36.00 ÷ $120.00 = 30%.
A discount is only as real as the price it is taken from; the Federal Trade Commission's Guides Against Deceptive Pricing (16 CFR Part 233) say a former price used for comparison should be one the item was actually offered at, openly and in good faith, for a reasonably substantial period.
Discount questions
How much is 20 percent off $100?
$20 off, so you pay $80.00. Multiply $100 by 0.20 for the saving, or by 0.80 for the price. With 7% sales tax on the discounted price, the total is $85.60.
How much is 30 percent off $50?
$15.00 off, leaving $35.00. Ten percent of $50 is $5, so 30% is $15. If a further 10% comes off at the register, it applies to $35, not $50: another $3.50 off, $31.50 in all — 37% off, not 40%.
How do you calculate a discount percentage?
Divide the amount off by the original price and multiply by 100. A price cut from $120 to $84 is $36 off, and $36 ÷ $120 = 30%. The Original price tab does this from the two prices.
Is 20% off and then 10% off the same as 30% off?
No — it is 28% off. The 10% applies to the price after the first discount: $100 × 0.80 × 0.90 = $72. The combined rate is 20 + 10 − (20 × 10 ÷ 100) = 28%.
Should a percent-off coupon be used before or after a dollar coupon?
Taking the dollar coupon after the percentage leaves a lower price. On $200 with 20% and 15% off, a $10 coupon after the percentages gives $126.00; before them, $129.20. The store's promotion terms set the order — the page shows both.
Is sales tax calculated before or after a discount?
After a store discount: the tax is on the price you pay. 7% on a $150 item at 25% off is 7% of $112.50, $7.88. A manufacturer coupon that the store is reimbursed for can still be taxed, as in Minnesota's Revenue Notice 05-06.
How do you find the original price before a discount?
Divide the sale price by one minus the discount. $84 at 30% off: $84 ÷ 0.70 = $120. Do not add 30% to $84 — that gives $109.20, because 30% of $84 is less than 30% of $120.
What is the difference between a discount and a markup?
A discount is a percentage of the higher, original price; a markup is a percentage of the lower cost. Taking 25% off $100 gives $75, but adding back 25% of $75 gives only $93.75; getting back to $100 needs a 33.33% markup.
Can a store advertise any former price for a discount?
The FTC's Guides Against Deceptive Pricing (16 CFR 233.1) say a former price used in a "was / now" comparison should be a price the item was actually and openly offered at, in good faith, for a reasonably substantial period. A discount from an inflated former price is not a real saving.
Source notes
Method, sources & limitations
Every figure on this page comes from the formula above applied to the values you enter. Nothing is estimated from market data, and no result is a forecast. These are the sources behind the method and any fixed figures it uses:
- Federal Trade Commission — Guides Against Deceptive Pricing, 16 CFR Part 233 (former-price comparisons)
- Rhode Island General Laws § 44-18-12 — "Sales price" (Streamlined Sales Tax definition: seller discounts and unreimbursed coupons excluded)
- Minnesota Department of Revenue — Revenue Notice 05-06, Sales price: discounts (store vs manufacturer coupons)
Educational information only. Results are estimates produced from the assumptions you enter, and are not financial, tax, legal or medical advice. Check anything that matters against a qualified professional and the cited sources.