A discount is just a percentage of the original price. To find the sale price, subtract that discount from the original price, or multiply the original price by the remaining percentage.
If you have more than one discount, do not add the percentages together unless the store says they apply to the same base in a simple way. Instead, apply each discount in order. That is how you handle stacked discounts, and it is also how you reverse a discount when you need the original price.
How a discount works
A discount reduces the original price by a stated percentage. If an item costs $100 and the discount is 20%, the discount amount is 20 and the sale price is 80.
You can think of the discount in two equivalent ways:
- Find the discount amount first, then subtract it.
- Find the percentage left to pay, then multiply the original price by that remaining fraction.
For the same $100 item with 20% off, you could also calculate the sale price as 80. Both methods give the same result.
If you want a quick refresher on percentage calculations, see the percentage calculator.
Find the discount amount
To calculate the amount saved, use this structure:
discount amount = original price × discount rate
Here is a worked example. A jacket has an original price of $80 and a discount of 25%. The amount saved is 20.
Then the final price is 60.
This is useful when a label shows “25% off” but you want to know the actual dollars saved before you buy. You can also use the same method for a larger item, such as a $250 appliance with 12% off. The discount is 30, and the sale price is 220.
Find the sale price after one discount
The sale price is the original price minus the discount amount. You can write it as:
sale price = original price × (1 - discount rate)
For example, a pair of shoes costs $60 and is marked 30% off. The sale price is 42.
This method is usually the fastest because it does both steps at once. If you are checking a receipt or comparing offers, it is often easier to multiply by the remaining percentage than to calculate the discount separately.
A related idea appears when you compare prices before and after a sale. If you need to measure how much the price changed overall, the percentage change calculator can help you check the difference between the original and final amounts.
Stacked discounts do not add
When discounts are stacked, each one applies to the new price after the previous discount, not to the original price again. That means you should multiply the remaining percentages, not add the discounts.
For example, suppose an item has a 20% discount and then an extra 10% discount on the reduced price. Start with $100:
- After 20% off, the price is 80.
- Then 10% off that reduced price gives 72.
The final price is 72, so the total discount is 28.
Notice that this is not the same as 30% off. The combined discount rate is 0.28. That is why 20% then 10% is 28% total, not 30%. The second discount is applied after the first one has already lowered the price.
A simple rule for stacked discounts
If you have several discounts in a row, use this pattern:
final price = original price × (1 - first discount) × (1 - second discount) × ...
For example, if the original price is $200 and the discounts are 15% and 5%, the final price is 161.5. If you try to add them as 20% total, you will get the wrong answer.
Worked examples
Here are a few complete examples you can follow.
Example 1: one discount
An item costs $150 and has 40% off.
- Discount amount: 60
- Final price: 90
Example 2: stacked discounts
A store gives 30% off, then an extra 20% off the sale price.
- Start price: $90
- After 30% off: 63
- After another 20% off: 50.4
If you add the discounts, you might think the total discount is 50%, but that would be wrong. The final price is based on the reduced amount after the first markdown.
Example 3: discount plus sale tax
If you want to compare the discounted price with tax included, calculate the discount first and then apply tax to the sale price. For a $120 item with 25% off, the sale price is 90. If sales tax is added after that, the taxed total is 90 plus tax on that amount.
For tax details, the sales tax calculator can help you separate the discount step from the tax step.
Reverse discount: find the original price
Sometimes you know the sale price and the discount rate, but not the original price. In that case, work backwards.
Use this formula:
original price = sale price ÷ (1 - discount rate)
For example, if an item is on sale for $72 after a 20% discount, the original price is 90.
This works because the sale price is the part that remains after the discount. If 20% was taken off, then 80% of the original price remains. So you divide by 0.80 to recover the original amount.
Another example: a bag costs $51 after a 15% discount. The original price is 60.
When a discount is marked up in two steps
Sometimes a shop advertises one discount and then another coupon or member discount. Treat each discount as a separate step unless the promotion terms say otherwise.
If you want to estimate the total effect before checking out, calculate the remaining fraction after each step and multiply them. For example, 10% off followed by 10% off again leaves 0.81 of the original price, which is not the same as 20% off once.
That pattern also helps you compare offers. If one store gives a single 20% discount and another gives 10% off twice, the two offers do not land on the same final price. The second offer is slightly less generous because the second 10% is taken from a smaller base.
For more detail on working backwards from a discounted amount, see how to calculate reverse percentages. If you need to compare the size of different percentage terms, the article on percentage vs. percentage points can help avoid confusion.
Quick way to check your answer
A good check is to ask whether the final price makes sense relative to the original. A 10% discount should leave most of the price intact. A 50% discount should cut the price in half. A stacked discount should always leave less than either discount on its own, but not by simple addition.
If your answer seems off, check these common mistakes:
- Adding stacked discounts instead of applying them one after the other
- Using the discount rate as the sale price instead of the amount saved
- Dividing by the discount rate instead of the remaining percentage when reversing the calculation
- Applying tax before discount when the offer is meant to be taken first
If you are working through several products or comparing offers from different stores, calculate the discounted price first for each item, then compare totals. That gives you a cleaner basis for deciding which offer is actually cheaper.
See also: Percentage and Percentage Change Calculator. For more background, see Wikipedia.
Frequently asked questions
- How do you calculate a discount price?
- Multiply the original price by the discount rate to find the amount saved, then subtract that from the original price. Or multiply the original price by the remaining percentage after the discount. Both methods give the same sale price.
- How do you find the percent off from the original and sale price?
- Subtract the sale price from the original price to find the amount discounted. Then divide that amount by the original price to get the discount rate. If you want a quick check, express the result as a percentage.
- Do stacked discounts add together?
- Not usually. A second discount applies to the reduced price after the first discount, so you multiply the remaining percentages instead of adding the discounts. For example, 20% off then 10% off is not 30% total.
- How do you calculate 20% off then 10% off?
- Start with the original price, multiply by 0.80 for the first discount, then multiply by 0.90 for the second discount. The combined effect is a 28% total discount, not 30%. The final price is based on the smaller amount after the first markdown.
- How do you reverse a discount to get the original price?
- Divide the sale price by the remaining percentage after the discount. If the discount is 20%, divide by 0.80. This recovers the original price before the markdown was applied.
- Should tax be calculated before or after a discount?
- Usually, you calculate the discount first and then apply tax to the reduced price, but the exact rule depends on the store and local tax rules. Check the receipt or policy if you need the legally correct total.
- What is the fastest way to estimate a sale price?
- Turn the discount into the fraction left to pay and multiply once. For example, 25% off means you pay 75% of the original price. That is often quicker than calculating the discount amount separately.
About this article
Written by Yahav Atia, WSO – the digital agency (wso.co.il) that owns and founded this site, with the help of AI, and passed automated quality checks before publication. Numbers in the worked examples were computed in code, not estimated.