Discount Calculator

"40% off" tells you the discount; it does not tell you the price. This calculator answers discount questions in all three directions: what a discount makes the final price, what the original price was before a known discount, and what percentage a markdown between two prices actually represents — each its own mode, each instant.

Final-price mode carries the two extras that trip people up at checkout. A stacked second discount handles "30% off + extra 20% off" offers correctly — the second cut applies to the already-reduced price, so the pair is a true 44% off, not 50%, and the effective-discount panel states the honest combined figure retailers' wording obscures. An optional tax field then applies GST/VAT/sales tax on the post-discount amount, matching how invoiced discounts are taxed in practice. Original-price mode reverses a known discount by division (₹840 after 30% off means ₹1,200 before), and %-off mode grades a "was/now" pair.

Everything works in nine currencies with a copyable summary, and it serves both sides of the counter: shoppers comparing offers in money rather than percentages, and sellers reversing the math to set a sale price that lands where margin needs it. The disclaimer's caveat is fair — whether tax applies before or after a discount, and how offers stack, ultimately follows the retailer's checkout rules.

The three modes are one identity read three ways. Final price = original × (1 − d/100); a stacked second discount multiplies again by (1 − d₂/100), which is why the combined discount is 1 − (1−d)(1−d₂) rather than d + d₂. Original price reverses by division: original = sale ÷ (1 − d/100). And % off compares two prices: (original − sale) ÷ original.

The tax option applies the rate to the post-discount amount — the sequence used when a discount appears on an invoice. The effective-discount insight recomputes the true single percentage of any stacked pair, making the marketing arithmetic transparent.

The calculator models percentage discounts (single or stacked) with optional post-discount tax — fixed-amount coupons are handled by comparing final prices manually, and retailer-specific stacking or tax rules can differ from the standard sequence, as the disclaimer notes. Original-price mode requires the discount to be below 100%. It computes prices; it does not know any store's actual promotion rules — checkout remains the arbiter.

Client-side arithmetic per mode: final = price × (1−d₁/100) × (1−d₂/100), with tax applied to the result when set and the effective percentage derived from the compound factor; original = sale ÷ (1−d/100), guarded against d ≥ 100; pctOff = (price − sale) ÷ price × 100. Nine-currency locale formatting; invalid states render a correction hint rather than results.

Shoppers converting offer wording into real prices, deal-comparers weighing coupons against percentages, sellers pricing sales to protect margin, and anyone who has stared at "extra 20% off at checkout" wondering what the item actually costs. Where the tax portion needs its own breakdown, the GST Calculator picks up the thread.