This discount calculator handles three scenarios
- Calculating the sale price from a discount percentage
- Working backwards to find what discount was applied, and
- Figuring out the true savings when two discounts are stacked.
Enter your numbers and the results appear instantly.
Whether you’re comparing prices on Black Friday, setting a promotional price for your store, or just double-checking a receipt, this tool gives you the exact numbers.
How Discount Calculations Work
Discount math boils down to one core idea: a percentage is always a fraction of something. Which “something” matters enormously, and that’s where most confusion comes from.
Calculating the Sale Price
This is the most common scenario. You know the original price and the discount percentage, and you want the final price.
Formula:
Sale Price = Original Price x (1 - Discount / 100)
Amount Saved = Original Price - Sale PriceExample: A $120 jacket is on sale for 25% off.
Sale Price = 120 x (1 - 25 / 100) = 120 x 0.75 = $90.00
Amount Saved = 120 - 90 = $30.00You pay $90. You save $30. Simple enough. The “multiply by the remaining percentage” approach is faster than calculating the discount and subtracting it separately, and it’s less prone to arithmetic errors.
Finding the Discount Percentage
Sometimes you see two prices and want to know the actual discount applied. A store might show a “was $89, now $67” tag without telling you the percentage.
Formula:
Discount % = ((Original Price - Sale Price) / Original Price) x 100Example: A phone was $349, now listed at $279.
Discount % = ((349 - 279) / 349) x 100 = (70 / 349) x 100 = 20.06%That’s about 20% off, though the store may have rounded in either direction when setting the price.
The Stacked Discount Trap: Why 20% + 10% Is Not 30%
This is the part that trips up a lot of people, including some retailers.
Stacked discounts are two (or more) discounts applied one after the other. A common example: a store offers 20% off everything, plus an extra 10% off for loyalty card holders. Many shoppers assume they’re getting 30% off. They’re not.
How stacked discounts actually work:
Original Price: $100
After 1st discount (20%): $100 x 0.80 = $80.00
After 2nd discount (10%): $80 x 0.90 = $72.00
Total Saved: $100 - $72 = $28.00
Effective Discount: 28%, not 30%The second discount of 10% applies to $80, not to the original $100. So that second discount is only saving you $8, not $10.
The math formula behind this is:
Effective % = 100 - (1 - D1/100) x (1 - D2/100) x 100For 20% and 10%: 100 - (0.80 x 0.90) x 100 = 100 - 72 = 28%
The gap between the expected total (30%) and the real total (28%) grows as the discounts get larger. Two 40% discounts don’t give you 80% off. The real effective discount is 64%.
This matters for retailers too. If you’re planning a “20% off, then an extra 10%” promotion, your margin hit is 28%, not 30%. The difference adds up quickly across high volumes.
How to Calculate Discounts in Excel
Excel doesn’t have a dedicated DISCOUNT function, but you can build these calculations with basic formulas in seconds.
Sale Price from a Discount Percentage
If your original price is in cell A2 and discount percentage is in B2:
=A2*(1-B2/100)If B2 already stores the value as a decimal (like 0.25 instead of 25), drop the division:
=A2*(1-B2)To get the amount saved:
=A2-A2*(1-B2/100)Or the shorter version:
=A2*B2/100Finding the Discount Percentage Between Two Prices
Original price in A2, sale price in B2:
=((A2-B2)/A2)*100If you format the result cell as a percentage in Excel, remove the *100 part:
=(A2-B2)/A2Then format the cell as Percentage (Ctrl+1, then Percentage). Excel will display 0.2001 as 20.01% automatically.
Stacked Discounts
Two discounts in B2 and C2, original price in A2:
After first: =A2*(1-B2/100)
After second: =A2*(1-B2/100)*(1-C2/100)
Effective %: =(1-(1-B2/100)*(1-C2/100))*100A Practical Excel Tip: Tiered Discounts with IF
If you’re setting up a pricing sheet where the discount depends on the order size, the IF function is the right tool:
=IF(A2>=1000, A2*0.85, IF(A2>=500, A2*0.90, A2*0.95))This applies 15% off for orders over $1,000, 10% off for $500 to $999, and 5% off for everything below $500.
One gotcha: if you store your discount rates as percentages in the cell (showing as “10%”), Excel stores them as 0.10 internally.
Double-check your formula isn’t dividing by 100 again when the value is already a decimal. Running =A2*(1-B2/100) when B2 contains 0.10 would give you A2 multiplied by 0.999, not 0.90.
Common Mistakes When Calculating Discounts
Adding stacked discounts together
Two sequential discounts never add up to their sum. Always calculate them step by step, or use the effective discount formula. The previous section covers the math in detail if you want to check your work.
Confusing discount with margin
A 20% discount does not reduce your margin by 20 percentage points. If your margin was 40% before the discount, it is not 20% after. Margin is calculated based on the selling price, which changes when you discount. The actual margin reduction depends on your cost of goods, not just the discount size.
Calculating the discount on the wrong base
When a store says “save $30 on a $150 item,” that’s a 20% discount. But if they show $30 off a $90 sale price, the original was $120 and the discount is 25%, not 33%. Always make sure you’re calculating the percentage against the correct base price.
Using rounded numbers for multi-step calculations
If you manually round intermediate results, errors compound. In the stacked discounts example above, rounding $80.00 to $80 is fine, but in more complex chains with three or four discounts, rounding after each step introduces cumulative error. Let the calculator (or Excel) carry the full decimals through to the final step, then round once at the end.
Mistaking cashback for a discount
A 10% cashback offer is functionally similar to a 10% discount, but there are differences. Cashback is paid after the transaction, often via a separate channel (app, card statement, etc.). You still pay the full price upfront. The actual value depends on whether you receive the cashback reliably and how you account for the time delay. For everyday comparisons, they’re close enough, but they’re not identical.
Frequently Asked Questions
How do I calculate 20% off a price?
Multiply the original price by 0.80. A $75 item at 20% off: 75 x 0.80 = $60. Alternatively, calculate 20% of $75 (which is $15) and subtract it: 75 – 15 = $60. Both methods give the same result. The multiply-by-the-remainder approach is faster when you’re doing this repeatedly.
What is the formula for discount percentage?
Discount % = ((Original Price – Sale Price) / Original Price) x 100. For example, if a $200 item sells for $160, the discount is ((200 – 160) / 200) x 100 = 20%. In Excel: =((A2-B2)/A2)*100 where A2 is the original price and B2 is the sale price.
Do two stacked discounts add up to their combined total?
No. Two stacked discounts applied sequentially are always less than their sum. A 20% discount followed by a 10% discount gives an effective discount of 28%, not 30%. Each additional discount applies to the already-reduced price, so the savings from the second discount are smaller than they appear.
How do I find the original price if I know the sale price and discount?
Divide the sale price by (1 – Discount / 100). If a $68 item was discounted 15%, the original price was 68 / (1 – 0.15) = 68 / 0.85 = $80. In Excel: =B2/(1-C2/100) where B2 is the sale price and C2 is the discount percentage.
Is a 50% markup the same as a 50% discount?
No. A 50% markup on a $100 cost gives a selling price of $150. A 50% discount on $150 brings it back to $75. The two operations are not symmetrical because they use different base values: markup uses cost, discount uses selling price.
How does a 30% discount affect my profit margin?
It depends on your original margin. If you sell an item for $100 with a 40% margin ($60 cost, $40 profit), a 30% discount drops the price to $70. Your new margin is ($70 – $60) / $70 = 14.3%. You’ve lost about 25.7 percentage points of margin on a 30% discount. The higher your original margin, the better you can absorb a discount without going into negative territory.
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