Two quick formulas cover almost every sale you'll see:
- Amount saved = original price × discount
- Sale price = original price × (1 − discount)
Write the discount as a decimal: 30% is 0.30, so the sale price is the original price × 0.70.
Example: 30% off $80. You save $80 × 0.30 = $24, and pay $80 × 0.70 = $56.
Percent-off chart
| Original price | 20% off | 25% off | 30% off | 40% off | 50% off |
|---|---|---|---|---|---|
| $20 | $16.00 | $15.00 | $14.00 | $12.00 | $10.00 |
| $35 | $28.00 | $26.25 | $24.50 | $21.00 | $17.50 |
| $50 | $40.00 | $37.50 | $35.00 | $30.00 | $25.00 |
| $60 | $48.00 | $45.00 | $42.00 | $36.00 | $30.00 |
| $80 | $64.00 | $60.00 | $56.00 | $48.00 | $40.00 |
| $100 | $80.00 | $75.00 | $70.00 | $60.00 | $50.00 |
| $150 | $120.00 | $112.50 | $105.00 | $90.00 | $75.00 |
| $200 | $160.00 | $150.00 | $140.00 | $120.00 | $100.00 |
| $300 | $240.00 | $225.00 | $210.00 | $180.00 | $150.00 |
Discount math in your head
- 10% off: move the decimal one place left to find the saving. 10% of $45 is $4.50.
- 20% off: double the 10% amount. $45 → $9 off → $36.
- 25% off: take a quarter off. $80 → $20 off → $60.
- 30% off: triple the 10% amount. $45 → $13.50 off → $31.50.
- 15% off: 10% plus half of 10%. $60 → $6 + $3 = $9 off → $51.
- 50% off: half price.
For bigger discounts, it's often easier to calculate what you pay: 40% off means you pay 60%. 60% of $75 is $45.
Stacked discounts don't add up
"Extra 20% off sale prices" sounds like 30% + 20% = 50% off. It isn't. The second discount applies to the already-reduced price:
$100 × 0.70 (30% off) × 0.80 (extra 20% off) = $56, a total discount of 44%, not 50%.
A few more:
- 40% off, then an extra 25% off: 55% off in total, not 65%.
- 50% off, then an extra 20% off: 60% off, not 70%.
The order of two percentage discounts doesn't matter, but mixing a dollar coupon and a percentage does. On a $100 item with a $10 coupon and 20% off:
- $10 off first, then 20%: ($100 − $10) × 0.80 = $72
- 20% off first, then $10: $100 × 0.80 − $10 = $70
Stores decide the order, so check which one they use.
"Buy one, get one" deals
- Buy one, get one free on equal-priced items is 50% off each item, but only if you want two.
- Buy one, get one 50% off is 25% off each item. Two $40 items cost $60 instead of $80.
Working backward
Find the original price from a sale price: divide by (1 − discount). If a jacket is $42 after 30% off, the original price was $42 ÷ 0.70 = $60.
Find the percent off from two prices: (original − sale) ÷ original × 100. A $120 item on sale for $90 is ($120 − $90) ÷ $120 = 25% off.
Don't forget sales tax
The discount comes first, then the tax is added to the sale price. 30% off $80 is $56, and with 8.25% tax you pay $60.62. See how to calculate sales tax for more.
Compare final prices, not percentages
A bigger discount doesn't always mean a better deal. 40% off a $150 jacket ($90) costs more than 20% off a $100 jacket ($80). Compare what you'll actually pay.
The Discount Calculator handles percent-off and dollar-off deals, stacked coupons and sales tax in one place. For other percentage questions, use the Percentage Calculator.
Frequently asked questions
How do I calculate 20% off?
What is 30% off $50?
Is 50% off plus an extra 20% off the same as 70% off?
Tools mentioned in this guide
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