Discount Calculator

See exactly what a sale price will be and how much you'll save. Supports an optional second (stacked) discount like "extra 20% off clearance."

How discounts are calculated

The formula is straightforward: sale price = original price × (1 − discount ÷ 100). A $60 jacket at 30% off costs 60 × 0.70 = $42, saving you $18.

Stacked discounts don't add up — they multiply

"30% off, plus an extra 20% off at checkout" is not 50% off. The second discount applies to the already-reduced price:

$60 → 30% off → $42 → extra 20% off → $33.60. That's an effective total discount of 44%, not 50%. Retailers rely on shoppers overestimating stacked deals — this calculator shows the true combined percentage.

Common discount shortcuts

Tip: instead of computing what comes off, compute what you pay. "40% off" simply means "pay 60%," and multiplying by 0.6 is one step.

Watch out for these sale tricks

• Inflated "original" prices: a 50% discount from a price nobody ever paid isn't a deal. Check price history when shopping online.
• "Up to X% off": usually only a few items hit the headline number.
• Percentage vs. dollar coupons: on a $25 purchase, "$10 off" beats "30% off" ($7.50). On $50, the 30% wins. Run both through the calculator.

The single discount that equals two stacked ones

Retailers stack discounts because two smaller numbers read as larger than the one they actually add up to. There is a formula for the true figure, and it is worth carrying: for discounts of a and b (as decimals), the equivalent single discount is a + b − a×b. The subtracted term is the part people miss — it is the second discount applied to money the first one already removed.

The last row is the one that makes the principle obvious: 50% off twice can never be free, because the second 50% applies to the half that is left. The gap between what is advertised and what you get widens as the discounts grow — at 20% + 20% you lose 4 percentage points, at 50% + 20% you lose 10.

One thing stacking does not depend on is order. 30% then 20% and 20% then 30% both land on 56% of list, because multiplication commutes. If a retailer insists the order matters, something other than arithmetic is going on — usually a coupon that applies before or after a category discount with different eligibility rules.

Working backwards from the sale price

Two questions come up constantly and both are the same division done in different places.

"It's $63 after 30% off — what was it originally?" Do not add 30%. $63 is 70% of the original, so divide: 63 ÷ 0.70 = $90. Adding 30% to $63 gives $81.90, which is wrong by nine dollars, and wrong in the direction that makes the deal look worse than it is.

"It was $90 and it's now $63 — what percentage off is that?" Divide the new price by the old, then subtract from 1: 1 − (63 ÷ 90) = 0.30, so 30% off. This is the calculation worth running on any "was/now" price tag, because it is the only way to check whether the advertised percentage matches the numbers printed beside it. They do not always.

Both of these are percentage-change problems in disguise; the percentage calculator handles them directly if you would rather not do the division.

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