Discount Calculator

Sale price and savings from a percent-off, dollar-off, or stacked-coupon discount.

Result

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General calculation reads

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How Not to Be Wrong

Jordan Ellenberg - math thinking

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The Joy of X

Steven Strogatz - accessible math

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Scientific calculator (Casio fx-991EX)

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How to use this calculator

Enter the original sticker price.
Pick the mode that matches the offer (single percent, single dollar, stacked combo).
For stacked combos, the 2nd discount applies to the already-reduced price — not to the original.
Set sales tax % only if you want the final out-the-door price; leave 0 for pre-tax comparisons.

About this calculator

Compute the sale price and your total savings from a discount — single percent off, single dollar off, or a stacked combo where a percent and a coupon (or two percents) apply in sequence. Stacked discounts are NOT additive: 15% off then 10% off the discounted price is a 23.5% combined discount (1 − 0.85 × 0.90), not 25%. The order matters too in some retailer policies, though mathematically two percent-off stacks commute (a × b = b × a). Optional US-style sales tax can be tacked on, computed (as is customary) on the post-discount price.

Frequently asked

Is "15% off plus 10% off" the same as 25% off?+

No. The 10% applies to the already-reduced price, so the combined discount is 1 − (0.85 × 0.90) = 23.5%, not 25%. Stacked percentage discounts always net to less than the sum of the parts.

Does order matter for two percent-off stacks?+

Mathematically no — multiplication commutes. (0.85 × 0.90 = 0.90 × 0.85). Some retailers apply order based on coupon rules; the math is the same.

Does sales tax come before or after the discount?+

Almost always after, in the US — tax is computed on the price you actually pay (post-discount). Many EU countries with VAT do the same.

What if my dollar coupon is more than the price?+

The calculator caps the savings at the original price — you don't get money back. (Some retailers do, but the math doesn't assume it.)

How do I calculate the percent saved from before/after prices?+

Use percentage-change: ((original − sale) / original) × 100. The "You save" line shows this implicitly. For a dedicated tool see percentage-calculator.