Sale price formula
$80 at 25% off: 80 × 0.75 = $60. You save 80 × 0.25 = $20.
How much did I save (percent)?
Was $45, now $36: (45 − 36) ÷ 45 × 100 = 20% off.
Stacked discounts (“extra 10% off sale prices”)
Discounts multiply — they don’t add. $100 with 20% off, then an extra 10%:
100 × 0.80 × 0.90 = $72 → a total of 28% off, not 30%.
Find the original price
Paid $51 after 15% off: 51 ÷ 0.85 = $60 original price.
Adding sales tax
In most U.S. states, tax is charged on the discounted price. $60 sale price with 8% tax: 60 × 1.08 = $64.80.
Quick discount chart
| Percent off | $20 item | $50 item | $100 item | $200 item |
|---|---|---|---|---|
| 10% off | $18.00 | $45.00 | $90.00 | $180.00 |
| 20% off | $16.00 | $40.00 | $80.00 | $160.00 |
| 25% off | $15.00 | $37.50 | $75.00 | $150.00 |
| 30% off | $14.00 | $35.00 | $70.00 | $140.00 |
| 40% off | $12.00 | $30.00 | $60.00 | $120.00 |
| 50% off | $10.00 | $25.00 | $50.00 | $100.00 |
FAQ
How do I calculate 20% off?
Multiply the price by 0.80. A $35 item at 20% off costs 35 × 0.80 = $28.
Is 20% off then 20% off the same as 40% off?
No. 0.80 × 0.80 = 0.64, so you pay 64% — a total discount of 36%.
How do I calculate 30% off in my head?
Find 10% (move the decimal), triple it, and subtract. $70: 10% = $7, 30% = $21, sale price = $49.
What’s the difference between a markup and a discount?
A markup is a percent added to cost; a discount is a percent taken off the price. A 25% markup followed by a 25% discount doesn’t get you back to the original.
Related
Run your own numbers.
Open percentage calculator →