Discount Calculator
The tag says 79.99, the sign says 30% off, the register says 69.99 and something feels wrong. This calculator takes the original price and the percentage off (or a flat dollar amount) and returns the true final price, the savings and the effective discount rate so you can spot suspicious math at the register.
How to calculate a discount
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1
Enter the original price
Type the list price before any discount is applied.
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2
Enter the discount
Pick percentage (e.g., 25%) or a flat amount (e.g., 10 off). Stack multiple discounts with the "add another" button.
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3
Read the result
See the final price, the savings, and the effective percent off when multiple discounts stack.
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4
Add tax (optional)
Toggle sales tax to see the at-the-register total. Tax is applied after discount, which is the standard US convention.
The formulas
- Percent off:
final = original * (1 - discount/100) - Savings:
original - final - Flat off:
final = original - amount - Effective rate when stacking:
1 - (1 - d1) * (1 - d2) * ...
Stacking is not additive. Two 20 percent discounts do not equal 40 percent; they equal 1 - 0.8 * 0.8 = 36 percent because the second discount applies to the already-reduced price.
Handy reference
| Percent off | Multiplier | Example on 100 |
|---|---|---|
| 10% | 0.90 | 90 |
| 15% | 0.85 | 85 |
| 20% | 0.80 | 80 |
| 25% | 0.75 | 75 |
| 30% | 0.70 | 70 |
| 40% | 0.60 | 60 |
| 50% | 0.50 | 50 |
| 60% | 0.40 | 40 |
| 70% | 0.30 | 30 |
| 75% | 0.25 | 25 |
Stack traps at the checkout
- “30% off, then extra 20% off sale items.” Effective 44 percent off, not 50.
- Coupon on already-discounted price. Usually allowed, but some retailers apply the coupon to the original price instead; check the fine print.
- Member discount applied to post-coupon total. Stacking order matters; a 10 percent member discount on an already-reduced 50 basket is 5 off, not 5 off the original 100.
- Tax on pre-discount price. Rare but it happens in some jurisdictions; read the receipt if the tax looks high.
Negotiation math
If a vendor offers two concessions, say 15 percent off and free shipping worth 20, compute whether the combined savings beat a single larger percentage. Often a clean “let’s just make it 300” offer is worth more than a stacked percentage plus a throw-in.
Frequently Asked Questions
After the discount, which is the default in the US, UK and most of the EU. If you need tax applied first (rare, but used in some jurisdictions on specific goods), toggle the “tax first” option.
Yes. Enter the sale price and the original price and the tool returns the implied percent off. Useful for checking whether “up to 60% off” actually delivered on your specific item.
A BOGO is a 50 percent discount on the total of the two items (if both cost the same). If the items differ in price, the discount usually applies to the cheaper item, yielding a less-than-50-percent effective rate. The tool has a BOGO mode for both cases.
Yes. Everything runs in your browser and no price data is uploaded.