1
Business & Marketing
Discount Calculator — Sale Price, Amount Saved & Final Price With Tax
Turn that '40% off, plus an extra 10%' sign into the real sale price and the true percent you save
Percent-off signs are everywhere — Black Friday doorbusters, clearance racks, "take an extra 15% off sale prices," coupon codes at checkout. The headline number looks like a simple deal, but the actual price you pay hinges on how those percentages are applied and, when there's more than one, how they combine. This calculator is built around that single job: turning percent-off and stacked-discount math into the exact dollars-and-cents sale price and the real amount you save.
The core formula is one line. Sale price = original price × (1 − discount ÷ 100). A $200 jacket at 20% off = 200 × (1 − 0.20) = 200 × 0.80 = $160. The amount you save is just the original minus the sale price: 200 − 160 = $40. A subtle flip catches people here: a 25%-off tag means you pay 75% of the price, so reach for 0.75, not 0.25, when you want the price you'll hand over.
Where shoppers really get tripped up is stacked discounts — a sale price with an extra coupon piled on top. The golden rule: stacked discounts multiply, they do not add. "20% off, then an extra 10% off" is not 30% off. The second percentage applies to the already-reduced price, so:
• After the first cut: $200 × 0.80 = $160 • After the second cut: $160 × 0.90 = $144
That works out to 1 − (0.80 × 0.90) = 28% off, not 30%. On a $200 item that's a $12 gap between what you expected and what you actually save — exactly the spread retailers count on you not noticing. The same logic answers the comparison question every coupon stacker eventually asks: is "40% off plus an extra 10%" better than a flat "45% off"? Multiply it out — 1 − (0.60 × 0.90) = 46% off — and yes, stacking wins, but by a single percentage point, not the 50% your gut guesses.
Reversing the math is just as useful. If you know the before-and-after prices, the effective discount = (1 − sale ÷ original) × 100, so a tag dropping from $200 to $150 is exactly 25% off. And to recover a missing original price, divide instead of multiply: an $80 shirt after 20% off started at 80 ÷ 0.80 = $100.
This calculator takes an original price and up to two stacked discount percentages, then returns the sale price, the dollar amount saved, and the effective total discount so you can compare offers on equal footing. If you also want the out-the-door figure, flip on the optional sales-tax line — but for the full breakdown of rates, exemptions, and which states charge none, see our dedicated Sales Tax Calculator.
📖 See also: How to Calculate a Tip (and Split the Bill)
Calculator
Fill in the fields and click "Calculate" for instant results.
📰 Formula
• Sale price = Original × (1 − D1/100) × (1 − D2/100) • Amount saved = Original − Sale price • Effective discount % = (1 − Sale/Original) × 100 • Original from sale = Sale price ÷ (1 − D/100) • Optional out-the-door = Sale price × (1 + Tax/100)
📰 Formula
• Sale price = Original × (1 − D1/100) × (1 − D2/100) • Amount saved = Original − Sale price • Effective discount % = (1 − Sale/Original) × 100 • Original from sale = Sale price ÷ (1 − D/100) • Optional out-the-door = Sale price × (1 + Tax/100)
🧪 Worked examples
2
Example 2
3
Example 3
4
Example 4
⚠️ Common mistakes
- Adding stacked discounts instead of multiplying (20% + 10% is 28% off, not 30%).
- Confusing the percent off with the percent you pay (25% off means you pay 75%).
- Multiplying by the original to undo a discount instead of dividing by (1 − D/100).
- Forgetting to divide the percent by 100 before multiplying.
💡 Tips
- Stacked discounts always multiply — apply them one after another, never add the percentages.
- To compare offers, look at the effective discount percent, not the headline numbers.
- Sales tax is just an optional final add-on here; for rates and exemptions use our Sales Tax Calculator.
Embed this calculator on your site
Copy the code below and paste it into the HTML of your site or blog.
<iframe src="https://www.calcnimbus.com/embed/discount-calculator" width="100%" height="500" frameborder="0" style="border:1px solid #eee;border-radius:12px"></iframe>
❓ Frequently asked questions
How do I calculate the sale price after a discount?
Sale price = original price × (1 − discount ÷ 100). A $200 item at 20% off = 200 × 0.80 = $160.
How much money do I save with a discount?
Amount saved = original price − sale price. A $200 item at 20% off saves you 200 − 160 = $40.
How do two stacked discounts work?
They multiply, not add. 20% off then an extra 10% off = original × 0.80 × 0.90, which is 28% off total — not 30%.
In what order should I apply two stacked discounts?
The order doesn't change the result — multiplication is commutative, so 20% then 10% gives the same $144 as 10% then 20%. What matters is that you apply each to the running price, never adding the percentages together.
What does 25% off actually mean for the price I pay?
You pay 100% − 25% = 75% of the original. A $40 item at 25% off costs 40 × 0.75 = $30.
How do I find the original price before the discount?
Original price = sale price ÷ (1 − discount ÷ 100). An $80 item after 20% off was 80 ÷ 0.80 = $100.
Is '40% off plus an extra 10%' the same as 50% off?
No. Multiplying gives 1 − (0.60 × 0.90) = 46% off, not 50%. Stacked discounts are always less than the sum.
How do I figure out the percent discount from two prices?
Discount % = (1 − sale price ÷ original price) × 100. From $200 to $150 = (1 − 150/200) × 100 = 25% off.
What single flat discount equals stacking 20% and 10%?
1 − (0.80 × 0.90) = 0.28, so the combined effect is a flat 28% off. To convert any two stacked discounts into one equivalent rate, multiply the amounts you pay and subtract from 100%.