Before building Discount Calculator, we checked calculator.net's discount calculator directly.
Stacked discount calculator: not supported, by their own admission
It handles a single discount cleanly, with the math shown step by step. But for sequential discounts — a coupon on top of a sale price, for instance — the page explicitly says it's out of scope and points you to a different tool, describing the stacking math as "more confusing."
Multiple discounts calculator, and why 20% + 10% isn't 30%
Each discount applies to what's left after the previous one, not to the original price. $100 → 20% off → $80 → another 10% off that $80 → $72. That's a 28% total discount, not the 30% you'd get by just adding the percentages. This tool makes that gap visible instead of leaving you to do the (wrong) math in your head.
Discount calculator with tax, for the real final number
Add a sales tax rate and it's applied to the already-discounted price — the number you'd actually see at checkout, not just the pre-tax savings.
