Discount Calculator
This calculator uses standard published formulas and is reviewed for calculation accuracy and clarity. The result is exact arithmetic, not an estimate.
A discount is a percentage taken off an original price. This calculator returns both the dollar savings and the sale price when a percent-off deal is applied. Enter the original price and the discount percentage — the reference table and examples below also show how to combine (stack) two discounts correctly, which is where most people get tripped up.
How It Works
Multiply the original price by the discount rate as a decimal to get the dollar savings, then subtract from the original price for the sale price. You can also get the sale price in one step: Original price × (1 − discount ÷ 100). For example, 25% off means you pay 75% of the price.
Stacked discounts are the common pitfall: a "20% off, then an extra 10% off" promotion is not 30% off. The second discount applies to the already-reduced price, so the combined effect is 1 − (0.80 × 0.90) = 28% off, not 30%.
Worked Examples
Example 1 — a quarter off. A $120 item at 25% off. Savings = $120 × 0.25 = $30. Sale price = $90.00.
Example 2 — an odd price. A $49.99 item at 15% off. Savings ≈ $7.50. Sale price ≈ $42.49.
Example 3 — stacked discounts. A $200 coat at 30% off, plus an extra 20% coupon. First: $200 × 0.70 = $140. Then: $140 × 0.80 = $112 — a 44% total reduction, not 50%.
What This Result Means
The savings figure is what you avoid paying; the sale price is what you actually pay before tax. A discount only reflects genuine value if the "original" price is real — a large percent-off a marked-up starting price can still leave you paying more than a competitor's everyday price, so compare final sale prices, not headline percentages.
Reading the Result
What common percent-off deals leave you paying (as a share of the original price):
- 10% off → pay 90%
- 25% off → pay 75%
- 33% off → pay ~67%
- 50% off → pay half
- "Buy one get one 50% off" → 25% off the pair, on average
These are exact conversions of the percentage, provided so you can gut-check a sale price at a glance.
When to Use This Calculator
Use it at checkout to confirm a sale price, to compare "40% off" at one store against "$30 off" at another, to check whether a stacked-coupon deal is as good as it sounds, or to work out the original price when only the sale price and percent-off are shown.
Limitations
- Applies a single percentage to one price; for stacked discounts, apply them one at a time (or see the worked example above).
- Does not add sales tax — apply the discount first, then use the Sales Tax Calculator on the sale price for the out-the-door total.
- Assumes the original price is genuine; it cannot tell you whether the pre-discount price was inflated.
- Dollar-amount ("$30 off") discounts need no percentage math — just subtract.
Frequently Asked Questions
Does this include sales tax?
No. Apply the discount first to get the sale price, then use the Sales Tax Calculator on that reduced amount to find the final price with tax.
How do I stack two discounts?
Apply the first discount, then apply the second to the already-reduced price — they do not add. A 20% then 10% discount is 28% off overall (0.80 × 0.90 = 0.72), not 30%.
What if the discount is in dollars, not a percentage?
Just subtract the dollar amount from the original price — no percentage conversion needed. To express it as a percentage, divide the dollar discount by the original price and multiply by 100.
How do I find the original price from a sale price?
Divide the sale price by (1 − discount ÷ 100). For example, a $90 sale price after 25% off was $90 ÷ 0.75 = $120 originally.
Is a bigger percent-off always the better deal?
Not necessarily. Compare final sale prices, not headline percentages — a 40% discount on an inflated price can cost more than a smaller discount on a lower everyday price.