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How to use the discount calculator
This discount calculator gives you the sale price, what you save and the real percentage off for any kind of markdown: a plain percent off, a dollar amount off, two or three discounts stacked on top of each other, or a sale price you want to turn back into the original. Pick the type at the top, type the price, and the result updates as you go.
- % off is the usual "25% off" tag. Tap a preset or type your own number.
- Amount off is for coupons like "$15 off your order". Tick the box if the amount comes off each item instead.
- Stacked handles "extra 20% off sale items" on top of an existing markdown, up to three layers.
- Original price works backwards from a sale price.
- Compare deals puts up to three offers side by side for the number of items you need.
Quantity and sales tax are optional. Tax is added after the discount, which is how most US stores ring it up. The table under the calculator lists 10% to 75% off the same price, and Save as PDF puts the whole calculation on one page.
How do you calculate a percent off?
Multiply the price by the share you still pay. 30% off means you pay 70%, so an $80 item costs 80 × 0.70 = $56. To see the saving on its own, multiply by the discount instead: 80 × 0.30 = $24.
Sale price = price × (1 − discount ÷ 100)
A shortcut for doing it in your head: 10% is the price with the decimal point moved one place left. For $80 that is $8, so 30% is three of those ($24) and 15% is one and a half ($12).
Common discounts on $80 and $50
| Discount | Save on $80 | Pay on $80 | Save on $50 | Pay on $50 |
|---|---|---|---|---|
| 10% off | $8.00 | $72.00 | $5.00 | $45.00 |
| 15% off | $12.00 | $68.00 | $7.50 | $42.50 |
| 20% off | $16.00 | $64.00 | $10.00 | $40.00 |
| 25% off | $20.00 | $60.00 | $12.50 | $37.50 |
| 30% off | $24.00 | $56.00 | $15.00 | $35.00 |
| 40% off | $32.00 | $48.00 | $20.00 | $30.00 |
| 50% off | $40.00 | $40.00 | $25.00 | $25.00 |
| 70% off | $56.00 | $24.00 | $35.00 | $15.00 |
Why 50% off plus 20% off is not 70% off
Because the second discount is applied to a price that is already reduced. Take a $100 pair of boots marked 50% off, with "an extra 20% at checkout". Half off leaves $50. 20% of $50 is $10, so you pay $40. That is 60% off the original, not 70%.
50% + 20%: 1 − 0.50 × 0.80 = 0.60 → 60% off
The order makes no difference: 20% first and then 50% also ends at $40. Discounts multiply, they don't add. Three stacked discounts of 30%, 20% and 10% come to 49.6% off, not 60%. Stacked mode shows the real total next to the number the ad seems to promise.
How do I find the original price before a discount?
Divide the sale price by the share you paid. If a jacket costs $42 after 30% off, you paid 70% of the original, so the original was 42 ÷ 0.70 = $60.
The usual mistake is adding 30% back on top: 42 × 1.30 = $54.60, which is too low. The percentage was taken from the bigger number, so you divide instead of multiplying. The same trick tells you whether a "was" price on a sale tag is believable.
Is buy 2 get 1 free better than 30% off?
That depends on how many you actually need, which is why Compare deals asks for that number first. Here is a $20 item under three offers:
| Items you need | 30% off | Buy 2, get 1 free | 3 for $50 |
|---|---|---|---|
| 1 | $14.00 | $20.00 | $20.00 |
| 2 | $28.00 | $40.00 | $40.00 |
| 3 | $42.00 | $40.00 | $50.00 |
| 4 | $56.00 | $60.00 | $70.00 |
| 6 | $84.00 | $80.00 | $100.00 |
Buy 2 get 1 free is a 33.3% discount, but only in full sets of three. Need two? You pay full price and walk out with a third item you didn't want. Need four? You pay for three of them. Unless your number is a multiple of three, 30% off is the better deal. The "3 for $50" multibuy saves just $10 on $60 worth of goods, a 16.7% discount that is easy to mistake for a bargain.
Discount first, then sales tax
In the US, a store's own discount lowers the price that sales tax is charged on. A $120 coat at 25% off in a place with 7% sales tax costs 90 × 1.07 = $96.30. Manufacturer coupons can work differently: some states tax the price before the coupon, because the manufacturer pays the store back. In the UK and most of Europe the shelf price already includes VAT, so leave the tax box at 0.
Stores round each line to the cent, so a receipt can be a cent away from what you see here. The rounding option takes the total to the nearest $0.05, $1 or $5, which is handy when you are setting sale prices for your own shop and want clean numbers.
Frequently asked questions
How do I calculate 30% off 80 dollars?
30% of $80 is $24, so you pay $56. The quick way is to multiply by what you keep: 80 × 0.70 = 56.
Is 50% off plus an extra 20% off the same as 70% off?
No, it works out to 60% off. The second discount is taken from the already reduced price: $100 becomes $50, then 20% off $50 leaves $40.
How do I find the original price from the sale price?
Divide the sale price by (1 − discount ÷ 100). A jacket that costs $42 after 30% off was 42 ÷ 0.70 = $60 before the sale.
How do I work out what percent off something is?
Subtract the sale price from the original, divide by the original and multiply by 100. A price cut from $80 to $60 is 20 ÷ 80 × 100 = 25% off.
Is sales tax charged before or after a discount?
For a store's own discount, sales tax is normally charged on the reduced price: $100 at 25% off with 8% tax costs 75 × 1.08 = $81. Some US states tax the full price when a manufacturer's coupon is used, so check your receipt.
Is buy 2 get 1 free better than 30% off?
Only if you want all three. Buy 2 get 1 free is 33.3% off three items, but if you need just two you pay full price for both, while 30% off saves you 30% on each.
How much is 15% off $45?
15% off $45 is $6.75, so the sale price is $38.25. Multiply 45 × 0.85 to get it in one step.