Discount Calculator
Sale price, percent off or original price — with stacked discounts and sales tax after the discount.
Prices are calculated in your browser — nothing is sentWork out the sale price, the percent off, or the original price
Type amounts the way your receipt shows them — 1,299.50 or 1.299,50 — and results follow the same format.
How this discount calculator works
Quick answer: to take a percentage off a price, multiply the price by the part you still pay. 25% off $80 is $80 × 0.75 = $60, and you save $20. The long way gives the same result — $80 × 0.25 = $20 off, then $80 − $20 = $60 — but multiplying by what is left is one step instead of two, and it is the form that stacks cleanly when a second discount arrives.
The calculator answers the three questions a price tag raises. Sale price after the discount: enter the original price and the discount, as a percentage or as a fixed amount, and it shows what you pay, what you save and the real total discount. What percent off is it: enter the original and the sale price and it gives the percentage — handy when the tag shows two prices but no percentage. Original price: enter the sale price and the discount and it works back to the price before the markdown, by dividing rather than adding.
Stacked discounts are where mental math goes wrong. "30% off plus an extra 20% at the register" is not 50% off: the second discount applies to the already-reduced price, so you pay 0.70 × 0.80 = 0.56 of the original — a 44% discount. The optional extra-discount field applies it exactly that way and prints the arithmetic, so you can see where the missing 6% went before you reach the register on Black Friday.
Sales tax is added after the discount. In the US and Puerto Rico shelf prices usually exclude the tax, so choose your state's rate or the 11.5% IVU and the calculator adds it to the discounted price, itemized like a receipt. In Mexico the price on the tag already includes IVA, so leave the tax off; the 16% IVA option is for quotes written "más IVA". Because both the discount and the tax are percentages, applying them in either order gives the same total — the order only matters for fixed-amount coupons.
Every amount is rounded to the cent at each step, the way a register rounds, so the lines always add up to the total shown. Type numbers the way your receipt writes them — 1,299.50 or 1.299,50 — and the results come back in the same format. Nothing leaves your browser: no account, no upload, no tracking of what you are shopping for.
Discount formulas
| To find | Formula | Example |
|---|---|---|
| Sale price | price × (1 − discount) | $80 × 0.75 = $60 |
| Amount saved | price × discount | $80 × 0.25 = $20 |
| Percent off | 1 − sale price ÷ original price | 1 − $599 ÷ $899 = 33.4% |
| Original price | sale price ÷ (1 − discount) | $75 ÷ 0.75 = $100 |
| Stacked discount | 1 − (1 − d₁) × (1 − d₂) | 1 − 0.70 × 0.80 = 44% |
| With sales tax | price × (1 − discount) × (1 + tax) | $1,000 × 0.80 × 1.115 = $892 |
How much off is it really? Common deals
For items at the same price, and only if you were going to buy all of them anyway:
| Deal | Real discount | Why |
|---|---|---|
| Buy one, get one free (BOGO) | 50% | You pay 1 price for 2 |
| Buy 2, get 1 free | 33.3% | You pay 2 prices for 3 |
| Buy 3, get 1 free | 25% | You pay 3 prices for 4 |
| Buy one, get one 50% off | 25% | You pay 1.5 prices for 2 |
| Second item 70% off | 35% | You pay 1.3 prices for 2 |
| 30% off + extra 20% off | 44% | 0.70 × 0.80 = 0.56 left to pay |
| 50% off + extra 20% off | 60% | 0.50 × 0.80 = 0.40 left to pay |
| 40% off + extra 10% off | 46% | 0.60 × 0.90 = 0.54 left to pay |
Discount formulas in Excel and Google Sheets
A2 = original price, B2 = discount (typed as 25%), C2 = extra discount, D2 = sale price
Sale price:
=A2*(1-B2)
Amount saved:
=A2*B2
Percent off (format the cell as Percentage):
=1-D2/A2
Original price from a sale price:
=D2/(1-B2)
Stacked discount:
=A2*(1-B2)*(1-C2)
With 8.25% sales tax, rounded to cents:
=ROUND(A2*(1-B2)*1.0825, 2)Common discount mistakes
| Mistake | Correct | Why |
|---|---|---|
| 30% + 20% = 50% off | 44% off | The second discount applies to the already-reduced price. |
| Original = $75 + 25% = $93.75 | $75 ÷ 0.75 = $100 | The 25% was a share of the original price, not the sale price. |
| Percent off = ($899 − $599) ÷ $599 | ÷ $899 → 33.4% | Divide by the original price. Dividing by the sale price gives 50.1%, the markup. |
| BOGO 50% = half price | 25% off each of two | Only the second item is half price. |
| =A2*(1-25) in Excel | =A2*(1-25%) | A plain 25 is 2,500%; add the % sign or divide by 100. |
FAQ
How do I calculate 25% off?
Multiply the price by 0.75, the part you still pay: 25% off $80 is $80 × 0.75 = $60. For other percentages, subtract the discount from 100 and use that: 30% off → × 0.70, 15% off → × 0.85. A mental shortcut: 10% is the price with the decimal point moved one place left ($80 → $8), so 30% off $80 is $80 − 3 × $8 = $56.
Why is 30% off plus an extra 20% not 50% off?
Because the extra 20% comes off the already-reduced price, not the original. On a $120 jacket, 30% off leaves $84; an extra 20% off $84 is $16.80, leaving $67.20 — you saved $52.80, which is 44% of $120. The formula is 1 − (1 − 0.30) × (1 − 0.20) = 0.44. Stacked discounts always add up to less than their sum.
What does BOGO 50% off mean?
"Buy one, get one 50% off" means the second item costs half, so on two items at the same price you pay 1.5 prices for 2 — 25% off each, not 50%. The full BOGO table: buy one get one free = 50% off, buy 2 get 1 free = 33.3%, buy 3 get 1 free = 25%. When the items cost different amounts, the discount almost always goes on the cheaper one, so the real saving is lower still.
Is sales tax charged before or after the discount?
After a store discount, in most US states: you pay tax on the reduced price. Mathematically the order would not change the total anyway, because both are percentages — price × 0.75 × 1.0825 equals price × 1.0825 × 0.75. The exception is manufacturer coupons: many states tax the price before the coupon, because the store is reimbursed for it. Rules vary by state, so check yours for coupons.
How do I find the original price from the sale price?
Divide the sale price by the part you paid: a $75 item at 25% off was $75 ÷ 0.75 = $100. Adding 25% to $75 gives $93.75, which is wrong — the 25% was a share of the original price, not of the sale price. The "Original price" mode does the division and shows both figures.