Percentages & Everyday Math
Discount Calculator
Get the sale price and how much you save.
Result
Example with the values filled in above
Final price
$96.00
You save $24.00 (20% off)
Discounted subtotal $96.00 + tax $0.00 + fees $0.00
Change any value and press Calculate for your own result.
Calculating…
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Two stacked discounts: the sum versus the real saving
- Sum of the two
- Actual discount
Show the numbers
| Coupons | Sum of the two | Actual discount |
|---|---|---|
| 10% + 10% | 20% | 19% |
| 20% + 10% | 30% | 28% |
| 20% + 20% | 40% | 36% |
| 30% + 20% | 50% | 44% |
| 50% + 20% | 70% | 60% |
| 50% + 50% | 100% | 75% |
How the discount calculator works
The calculator starts from the original price times quantity, applies the main discount, then any second stacked discount to the already-reduced amount, adds sales tax on the discounted subtotal, and finally adds shipping or fees. You see the final price and exactly how much you saved.
Formulas
Sale price = price × (1 − discount ÷ 100)
Stacked: final = price × (1 − d₁ ÷ 100) × (1 − d₂ ÷ 100)
Total = discounted subtotal + tax + shipping
Worked examples
- $120 with 20% off — 120 × 0.80 = $96, saving $24.
- $120 with 20% off + extra 10% off — 120 × 0.80 × 0.90 = $86.40. The combined discount is 28%, not 30%, because the second discount applies to the reduced price.
- Adding 8% tax — $86.40 × 1.08 = $93.31 at checkout.
Why stacked discounts never add up
Two coupons of 20% and 10% feel like 30% off, but they are not — the second is taken from the already-reduced price, so the real saving is 28%. The order does not change the final total (0.8 × 0.9 equals 0.9 × 0.8), but it always lands below the simple sum. The only case where percentages truly add is when both are calculated from the original price, which is rare in retail.
Percent-off vs. amount-off deals
Deals come in two forms: a percentage off ("20% off") or a fixed amount off ("$25 off"). Which wins depends on the price — $25 off beats 20% off on anything under $125, but 20% off pulls ahead above it. When you are choosing between coupons, convert both to a final price and compare; the calculator's saved-amount figure makes that comparison quick.
BOGO offers in percentage terms
| Offer | Equivalent discount | Condition |
|---|---|---|
| Buy one get one free | 50% off | Only if you wanted two |
| Buy one get one half price | 25% off | Across both items |
| Buy two get one free | 33.3% off | Across all three |
| Buy three get one free | 25% off | Across all four |
| 3 for the price of 2 | 33.3% off | Same as buy two get one free |
The condition column is the whole story. A BOGO is only 50% off if the second item was something you would have bought anyway. If it was not, the discount on what you actually wanted is zero, and you have spent more than you planned.
Discounts in Excel and Google Sheets
| Goal | Formula |
|---|---|
| Price after discount | =A2*(1-B2) |
| Amount saved | =A2*B2 |
| Two stacked discounts | =A2*(1-B2)*(1-C2) |
| Discount % from two prices | =(A2-C2)/A2 |
| Original price from sale price | =C2/(1-B2) |
| Discount then tax | =A2*(1-B2)*(1+D2) |
Enter 20% either as 0.2 in a plain cell or as 20% in a percentage-formatted one — never
both, or the discount silently becomes 0.2%.
The percent off formula
Taking a percentage off is one multiplication. The step that trips people up is that the discount amount and the final price are two different numbers:
saving = price × percent ÷ 100 · final price = price × (1 − percent ÷ 100)
| Price | Discount | You save | You pay |
|---|---|---|---|
| $30 | 20% | $6.00 | $24.00 |
| $30 | 50% | $15.00 | $15.00 |
| $40 | 25% | $10.00 | $30.00 |
| $40 | 30% | $12.00 | $28.00 |
Going the other way — finding the discount percentage from two prices — divide the saving by the original price: an item cut from $80 to $60 saved $20, and 20 ÷ 80 = 25% off.
Discount and sales tax in the right order
Discount first, tax second. Sales tax and VAT apply to the amount actually charged, so a coupon reduces the taxable base as well as the price:
total = price × (1 − discount) × (1 + tax rate)
A $40 item at 25% off with 8% sales tax costs $30 × 1.08 = $32.40. Applying tax first gives the same answer here because multiplication commutes — but only when the discount is a true price reduction. Manufacturer coupons reimbursed to the retailer are often taxed on the pre-coupon price, which is why a receipt sometimes shows more tax than you expect.
UK and EU shelf prices already include VAT, so a "20% off" sign there reduces a gross price and no further tax is added at the till.
To add or strip tax on its own, use the VAT / sales tax calculator, or check the underlying math with the percentage calculator.
Discount Calculator — frequently asked questions
What is the percent off formula?
Final price = price x (1 - percent/100), and the saving is price x percent/100. A $40 item at 25% off saves $10 and costs $30.
How do I calculate percent off in Excel?
With the price in A2 and the discount in B2, use =A2*(1-B2) for the final price and =A2*B2 for the saving. Enter 20% either as 0.2 or as 20% in a percentage-formatted cell, never both.
How do I find the discount percentage from two prices?
Divide the saving by the original price. From $80 down to $60 you saved $20, and 20/80 gives 25% off.
Is discount applied before or after sales tax?
Before. Tax applies to what you actually pay, so a $40 item at 25% off with 8% tax comes to $30 x 1.08 = $32.40. Manufacturer coupons can be an exception and are sometimes taxed on the pre-coupon price.
How is the sale price calculated?
The original price is multiplied by (1 − discount ÷ 100). A $60 item with 25% off costs 60 × 0.75 = $45, saving you $15.
How do stacked (double) discounts work?
The second discount applies to the already-discounted price, not the original, so discounts do not simply add up. 20% off followed by 10% off leaves 0.8 × 0.9 = 72% of the price — a 28% total discount, not 30%.
Is sales tax applied before or after the discount?
After the discount, which is how most stores calculate it. The calculator applies tax to the discounted subtotal and then adds any shipping or fees.
How much do I save with 20% off?
You save one fifth of the original price: original × 0.20. On a $85 purchase, 20% off saves $17 and you pay $68 before tax.