What this calculator does
See what you'll pay on sale and how much you'll save when something is a percent off. You can stack a second discount, such as a coupon. You can add sales tax at a rate you enter. You can also work backward from the original and sale prices to find the percent off. A table lists the price at common discounts from 10% to 75%.
A percent-off discount takes a share of the original price away. So 25% off means you pay 75% of the tag price. When a coupon goes on top of a sale, it comes off the already-reduced price, not the original. That's why 20% off plus 10% off isn't 30% off.
Where it's used
Why this math matters outside the classroom:
- Sale prices. Taking 30% off an $80 pair of shoes leaves a sale price of $56.
- Stacked discounts. An extra 10% off an item already 20% off leaves 72% of the price, a total of 28% off rather than 30%.
- Finding percent off. A jacket marked down from $120 to $90 is 25% off.
- Tax after discount. Shoppers add sales tax to the discounted price, not the original tag price, to find what they will pay at the register.
Grade level and standards: Grade 7; Common Core State Standards for Mathematics 7.RP.A.3. © Copyright 2010. National Governors Association Center for Best Practices and Council of Chief State School Officers. All rights reserved.
How to use it
- Choose what you want to find: the sale price from a percent off, or the percent off from two prices.
- Enter the original price and the discount percentage. In the second mode, enter the sale price instead.
- If a second discount applies, such as a coupon at checkout, tick the box and enter its percentage.
- If you like, enter your sales tax rate to see the price at checkout.
- Read the sale price and the amount saved. For two discounts, you'll also see the combined discount. Open the table to compare other common discounts on the same price.
What the inputs mean
- Original price
- The regular price before any discount.
- Discount
- The percent off, from 0% to 100%.
- Apply a second discount on top (for example, a coupon)
- Takes a second percent off the price that's left after the first discount.
- Second discount
- The second percent off, from 0% to 100%. It comes off the reduced price, not the original.
- Sale price
- The price you're actually being charged. If it's higher than the original, the result is negative, which means the price went up.
- Sales tax rate (optional)
- Optional. Your combined state and local sales tax rate. Tax is charged on the discounted price, which is how most US stores handle percent-off sales. Look up the rate for where you live; none is built in.
Formula and method
sale price = price × (1 − discount ÷ 100) two discounts: final = price × (1 − d1 ÷ 100) × (1 − d2 ÷ 100) saved = price − final combined discount = saved ÷ price × 100 percent off = (original − sale) ÷ original × 100 price with tax = sale price × (1 + tax rate ÷ 100)
In the formulas, d1 and d2 are the first and second discounts, as percents. Each discount multiplies the current price by the share that's left after the percent comes off. For example, 25% off leaves 0.75 of the price.
With two discounts, those shares are multiplied one after the other. So the second discount only works on the already-reduced price. That's why the total saving comes out less than the two percents added together. The order doesn't matter: 20% then 10% gives the same result as 10% then 20%.
Worked example
A $100 jacket is 20% off, and you have a coupon for an extra 10% off.
- After the first discount: $100 × (1 − 0.20) = $80.
- After the coupon: $80 × (1 − 0.10) = $72.
- Saved: $100 − $72 = $28, which is 28% of the original price.
- With 8.25% sales tax: $72 × 0.0825 = $5.94 of tax, so $77.94 in total.
Result: You pay $72. The two discounts together are worth 28% off, not 30%. With an 8.25% sales tax on the $72, you pay $77.94 at checkout.
Understanding the result
The sale price is what you pay before tax and shipping. The savings figure is how much less that is than the original price you entered.
Prices are shown to the cent. A $79.99 item at 25% off works out to $59.9925, which shows as $59.99. A store may round its own way.
Assumptions and limitations
- Discounts are percentages. Fixed-amount coupons, such as $10 off, aren't covered.
- A second discount comes off the already-discounted price. That's how stacked percent-off offers usually work.
- Sales tax is optional. It's charged on the discounted price, at the rate you enter. Shipping and other fees aren't included.
- Stores have their own rules on whether coupons can be combined, and in what order. Check the terms of the offer.
- Deals like buy-one-get-one or "spend $50, save $10" can't be entered directly. If you can, turn them into a matching percent off first.
- Results are estimates. The total at the register is what counts.
Frequently asked questions
Are two 50% discounts the same as getting it free?
No. The first 50% halves the price, and the second halves what's left. So you pay 25% of the original, which is a 75% combined discount.
How do I find the discount percent from the original and sale prices?
Subtract the sale price from the original, divide by the original, and multiply by 100. A $60 item selling for $45 is (60 − 45) ÷ 60 × 100 = 25% off. Choose "Percent off from two prices" above to do this for you.
Does the order of two discounts matter?
Not for two percent discounts: multiplying gives the same result in either order. It does matter when one discount is a fixed dollar amount. Taking dollars off first leaves less for the percent to work on.
Is sales tax calculated before or after the discount?
In most places tax is charged on the discounted price. Enter your rate in the optional sales tax field to see the total at checkout.
How much is 30% off $50?
$35. Thirty percent of $50 is $15, and $50 − $15 = $35. A quicker way is to multiply by what you keep: $50 × 0.70 = $35.
Is 40% off better than buy one, get one half off?
Buy one, get one half off on two equal items is 25% off the pair, because you pay 1.5 prices for 2. So 40% off is the better deal, and you don't have to buy two.
How this calculator is checked
Method: Percentage reduction of an amount; successive discounts as multiplied remainders; percent off as (original − sale) ÷ original; tax as a percentage of the discounted price. The calculation is covered by automated tests with known reference values and edge cases. Last updated 2026-10-18. Found a problem? Tell us.
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