How this calculator works
Each percentage discount multiplies the current price by (1 − discount). Stacked discounts multiply, which is why 25% off plus an extra 20% off is a 40% total discount, not 45%. A dollar coupon is subtracted after the percentage discounts, then sales tax is added.
Sale price = Price × (1 − D1%) × (1 − D2%) − Coupon
Total discount % = (Price − Sale price) ÷ Price × 100
Worked example
Using the default values in the calculator above:
| Input | Value |
|---|---|
| Original price | $80 |
| Discount | 25 % |
| Extra discount (taken after) | 0 % |
| Coupon | $0 |
| Sales tax | 0 % |
| Result | Value |
|---|---|
| Final price | $60 |
| You save | $20 |
| Total discount | 25 % |
| Price after first discount | $60 |
| Price before tax | $60 |
| Sales tax | $0 |
Step by step:
- After 25% off: $80 × 0.75 = $60
- After extra 0% off: $60 × 1 = $60
- Minus $0 coupon = $60
- Plus 0% tax = $60
Common mistakes to avoid
- Adding stacked discounts together — 30% + 20% off is 44% off, not 50%.
Frequently asked questions
What is 25% off $80?
$60 — you save $20.
Is 25% plus 20% off the same as 45% off?
No. It is 1 − 0.75 × 0.80 = 40% off.