Stacked Discount Calculator
Sale price plus an extra 20% off, then a coupon: enter the discounts in the order the shop applies them to see the final price, the real total discount and each step
The Price and the Discounts
Discounts, in the order they are applied
Leave a discount empty to skip it. With percentages the order does not change the price; with a fixed amount (a coupon) it does.
Type plain numbers; a decimal point or comma both work. Any currency. Your inputs stay in your browser.
You save 28.00 of 100.00 before tax, which is 28% in total.
Adding the percentages gives 30% off and a price of 70.00 before tax. Stacking them really takes 28% off, so the price is 72.00: 2.00 more than the simple sum suggests.
Calculated without rounding. A shop that rounds every step to the cent can differ by a cent or two.
How to use it
- Choose whether you want the final price or, from what you paid, the original price.
- Enter the price, then the discounts in the order the shop applies them. Pick “% off” for a percentage and “amount off” for a coupon of a fixed value.
- Add the sales tax or VAT if you want the price you will really pay.
- Read the final price, the real total discount, each step and, where it applies, the comparison with simply adding the percentages.
- Copy Result keeps the key figures for a message.
Worked example
A jacket costs 100. It is 20% off, and then there is an extra 10% off at the till, plus 8% sales tax. After the first discount: 100 × 0.80 = 80.00. After the second: 80.00 × 0.90 = 72.00. Tax: 72.00 × 1.08 = 77.76. You save 28.00 before tax, which is 28% in total, not 30%: adding the percentages would suggest 70.00. Reverse it: if you paid 77.76 with 8% tax and those two discounts, the original price was 77.76 ÷ 1.08 ÷ 0.90 ÷ 0.80 = 100.
Why this tool exists and where its numbers come from
Stacked offers are easy to misjudge: 20% off and then an extra 10% off is not 30% off. The tool multiplies the share that remains after each percentage, as the open business-math textbook below explains. The source covers chained percentage discounts and the equivalent single discount; it does not cover fixed-amount coupons, sales tax or any shop’s rounding, which the tool treats as plain arithmetic.
Sources
For the full method, see the Methodology section just below.
Methodology
The formulas. A percentage discount d leaves the share (1 − d) of the price. Two or more in a row multiply: final = price × (1 − d₁) × (1 − d₂) × …, and the single discount that gives the same result is 1 − (1 − d₁) × (1 − d₂) × …, never the sum. A fixed amount is subtracted from the price at that step. Tax is added after the last discount: × (1 + t). In reverse mode the tax is removed first, then each discount is undone from the last to the first: divide by (1 − d) for a percentage, add back a fixed amount.
Where stacked discounts mislead
Each slip below can be reproduced with the tool. The first four start from a price of 100.
- Adding the percentages. 20% off and then 10% off leaves 80.00 × 0.90 = 72.00, a total discount of 28%, not 30%.
- Two halves. 50% off and then another 50% off leaves 25.00, which is 75% off, not “free”.
- The order of a coupon. A fixed coupon of 20 and then 10% off gives (100 − 20) × 0.90 = 72.00; 10% off first and then the coupon gives 90.00 − 20 = 70.00.
- A longer chain. 30%, 10% and 5% off one after another leave 59.85, a total discount of 40.15%, not 45%.
- Tax on the wrong amount. 72.00 plus 8% tax is 77.76. Taking the 8% from the original 100 instead gives 80.00, which is 2.24 more. Some shops do charge tax before a coupon, so check your receipt.
Estimate for information only, not financial advice.
Frequently asked questions
Is 20% off plus 10% off the same as 30% off? ▼
No. The second discount applies to the price already reduced by the first, so 100 becomes 80.00 and then 72.00. The total discount is 28%, not 30%.
Does the order of the discounts matter? ▼
Not for percentages: 20% then 10% gives the same price as 10% then 20%. It does matter when one discount is a fixed amount, such as a 20 coupon: the coupon comes off a larger price if it is applied first.
How do I calculate two successive discounts? ▼
Multiply the price by (1 − first discount) and then by (1 − second discount). For 20% and 10%: 100 × 0.80 × 0.90 = 72.00. The tool does this for up to four discounts and shows each step.
Can I find the original price from what I paid? ▼
Yes. Choose “Original price (reverse)” and enter the price you paid and the discounts the shop applied. The tool removes the tax and then undoes each discount from the last to the first.
Is the tax applied before or after the discounts? ▼
This tool adds it after the last discount, which is the most common way. Rules differ by shop and country, so check your receipt if the totals do not match.
Is this the same as the percentage calculator? ▼
No. The percentage calculator handles one percentage at a time. This one chains several discounts, mixes percentages with fixed-amount coupons, adds tax and can work backwards.