Discount Calculator

A discount reduces a price by a percentage or fixed amount. Final price = original × (1 - discount_percent/100), or original - flat_discount. Savings is the difference between original and final price.

Enter original price and discount percentage to see final price and absolute savings. Stack multiple discounts (sequential, not additive) by feeding output back as input — a 20% then 10% sequence yields 28% off, not 30%.

The math is grade-school arithmetic, but stacking is where most people get it wrong. Each percentage applies to the already-discounted price, not the original. So 20 off then 10 off becomes 100 → 80 → 72, which is 28 total off. To compute the equivalent single percentage from a sequence: 1 - (1 - d1) × (1 - d2) × ... × (1 - dn). For 20 off then 10 off: 1 - 0.8 × 0.9 = 1 - 0.72 = 0.28, or 28 percent. To stack three discounts of 25, 15, and 10 percent: 1 - 0.75 × 0.85 × 0.90 = 1 - 0.574 = 0.426, or about 43 percent total — well below the 50 percent that adding the discounts would suggest.

A worked example. A jacket originally $200, marked down 30 percent in a sale, with an additional 15 percent off coupon at checkout. After the markdown: $200 × 0.7 = $140. After the coupon: $140 × 0.85 = $119. Total off: $81, or 40.5 percent. Add 8 percent sales tax (applied after discount in most US jurisdictions): $119 × 1.08 = $128.52. The 'half off' feel of the cumulative discounts disappears once tax goes on. Conversely, a single '40 percent off' coupon would yield $200 × 0.6 = $120, slightly more than the stacked discount, despite the headlines suggesting otherwise.

Limitations and edge cases. Sales tax application varies by jurisdiction and discount type. Manufacturer coupons that the brand reimburses to the retailer are sometimes taxed pre-discount because the retailer is being paid by both the consumer and the brand. Retailer-issued coupons reduce the taxable base. Most US states tax post-discount; some categories (clothing under $110 in NY, food everywhere) have separate rules. BOGO (buy one get one free) is mathematically a 50 percent discount on the bundle if both items are needed; if only one is needed, the 'free' item is overhead. Tiered discounts ('20 percent off orders over $100') create cliff behavior — a $99 order pays full price and a $101 order pays $80.80 plus tax. Loyalty point redemptions usually count as a payment method rather than a discount, which changes whether tax applies to the points-paid portion. Read the fine print or run two scenarios to see which the retailer is doing.