How to use this calculator
Choose what you want to find at the top:
- Sale price. Enter the original price and the discount, as a percentage or a dollar amount. Turn on Extra discount for a second percentage taken off the reduced price (an “extra 20% off sale items” offer), and add your sales tax rate if you want the price at the register.
- Original price. Enter what something costs on sale and the percent off to see what it cost before.
- Percent off. Enter the original and sale prices to see how big the discount really is.
The result breaks the original price into what you pay and what you save, shows each step, and lists the sale price at common discounts so you can compare offers at a glance.
The discount formulas
The amount you save is the price times the discount rate, and the sale price is what’s left:
Stacked discounts multiply. Two discounts of a% and b% together come to:
Sales tax is then added to the discounted price. To reverse a discount, divide instead of multiplying: original price = sale price ÷ (1 − d/100).
Each discount and the tax are rounded to the nearest cent, the way a register rounds them.
Worked examples
A single discount. A $80 pair of shoes is 25% off. You save 0.25 × $80 = $20, and pay $60.
Stacked discounts with tax. The same shoes are in an “extra 10% off sale prices” promotion, and your sales tax rate is 7%. After 25% off you’re at $60. The extra 10% takes off another $6, for a sale price of $54.00. Tax adds $3.78, so you pay $57.78. You saved $26, which is 32.5% of the original price, not the 35% the two numbers suggest.
Another one with tax. A $120 jacket at 30% off costs $84.00 before tax. With 8.25% sales tax you pay $90.93.
Working backward. A receipt shows $60 after 25% off. The original price was $60 ÷ 0.75 = $80. Likewise, $45 after 40% off was originally $75, and $84 after 30% off was $120.
Finding the percent off. A $50 item marked down to $35 is ($50 − $35) ÷ $50 = 30% off.
Common discounts on an $80 item
| Discount | You save | Sale price |
|---|---|---|
| 10% off | $8.00 | $72.00 |
| 15% off | $12.00 | $68.00 |
| 20% off | $16.00 | $64.00 |
| 25% off | $20.00 | $60.00 |
| 30% off | $24.00 | $56.00 |
| 33% off | $26.40 | $53.60 |
| 40% off | $32.00 | $48.00 |
| 50% off | $40.00 | $40.00 |
| 60% off | $48.00 | $32.00 |
| 70% off | $56.00 | $24.00 |
| 75% off | $60.00 | $20.00 |
The calculator builds this table for whatever price you enter, with a column for the after-tax price when you add a tax rate.
Stacked discounts compared
What two discounts in a row really add up to, on a $100 item:
| First discount | Then extra | Combined discount | You pay |
|---|---|---|---|
| 20% | 10% | 28% | $72.00 |
| 20% | 15% | 32% | $68.00 |
| 25% | 10% | 32.5% | $67.50 |
| 30% | 20% | 44% | $56.00 |
| 40% | 20% | 52% | $48.00 |
| 50% | 20% | 60% | $40.00 |
| 50% | 50% | 75% | $25.00 |
The order doesn’t matter: 20% then 10% is the same as 10% then 20%. What matters is that the second discount always applies to a smaller number, so “50% off plus an extra 50% off” is 75% off, not free.
Tips for shoppers
- Compare the final price, not the percentage. 30% off a $90 list price ($63) beats 40% off a $110 one ($66).
- Check which price an extra discount uses. “Extra 20% off” normally means off the sale price. If a promotion takes it off the original price, the total discount is the plain sum, which is better for you.
- Dollars off vs. percent off. $20 off is worth more than 20% off on anything under $100, and less on anything over $100.
- Budget for tax. Rates vary by state and city. The sales tax calculator adds tax to any price or backs it out of a total.
- Know what you’re comparing to. A discount is only as real as the “original” price it’s measured from. Prices tracked over a few weeks are a better guide than a crossed-out tag.
If you sell things rather than buy them, the markup calculator and margin calculator show how a discount eats into profit. For any other percentage question, the percentage calculator covers percent of a number and percent of a whole, and the percentage change calculator shows the percent increase or decrease between two prices.
Assumptions
The calculator applies the first discount, then any extra percentage to the reduced price, then sales tax to the final sale price, rounding each amount to the cent. Stores sometimes round differently or apply coupons in a different order, so a receipt can differ by a cent or two. Shipping, fees and coupon tax rules aren’t included.
Sources
- Sales Tax: Coupons, Discounts and Rebates (Publication ANJ-9), New Jersey Division of Taxation, an example of how store and manufacturer coupons are taxed differently
Frequently asked questions
How do I calculate a discount?
Multiply the price by the discount percentage as a decimal to get the savings, then subtract it from the price. For 25% off $80, the savings are 0.25 × $80 = $20 and the sale price is $60. The quick way is to multiply by what's left, 0.75 × $80 = $60.
How do I work out 20% off in my head?
Find 10% by moving the decimal point one place to the left, then double it. For a $64 item, 10% is $6.40, so 20% is $12.80 and you pay $51.20. For 30%, triple the 10% figure; for 5%, halve it.
Is 25% off plus an extra 10% off the same as 35% off?
No. The extra 10% is taken from the already-reduced price, so the two discounts multiply. On $80, 25% off gives $60, and 10% off that is $6, for a final $54. That's 32.5% off in total, not 35%.
How do I find the original price from the sale price?
Divide the sale price by 1 minus the discount as a decimal. If you paid $60 after 25% off, the original price was $60 ÷ 0.75 = $80. Adding 25% to $60 gives $75, which is wrong because the discount was a share of the original price.
Is sales tax charged on the original price or the sale price?
Usually on the price you actually pay, after store discounts. Manufacturer coupons are often treated differently, because the store is reimbursed for them; New Jersey, for example, charges tax on the full pre-coupon price. Rules vary by state, so check yours for a large purchase.
How do I calculate what percent off something is?
Subtract the sale price from the original price, divide by the original price and multiply by 100. A $50 item on sale for $35 is ($50 − $35) ÷ $50 × 100 = 30% off. Use the calculator's Percent off mode to do it for any two prices.
Updated November 2026. Results are estimates for educational purposes and depend on the inputs you provide.