Why 30% Off Then 20% Off Isn't 50% Off

"30% off — plus an extra 20% at checkout!" It reads like 50% off, and stores are happy to let you believe it. But stacked discounts don't add up the way they look. The second discount comes off the already-reduced price, not the original — so two cuts that seem to total 50% actually save you less. Knowing the real number is the difference between a good deal and a good-looking one.

Why 30% then 20% isn't 50%

Take a $100 item. Thirty percent off brings it to $70. The extra twenty percent comes off that $70, not the original $100 — so it's a $14 reduction, landing you at $56. You saved $44, an effective discount of 44%, not 50%. The gap is always in the store's favour, and it grows with bigger numbers. This isn't a trick you can out-argue; it's just how percentages of percentages work.

The number that lets you compare

The useful figure is the effective discount — the single percentage that would give the same final price. It's the honest way to compare offers. "40% off" at one shop can beat "30% plus 15%" at another, even though the second sounds bigger, because stacked percentages never combine to their sum. Our Discount Calculator takes both discounts, shows the final price, the exact amount saved, and that effective rate — so you can line up two deals side by side and see which actually wins. It runs entirely in your browser.

Don't forget the tax at the till

In many places the advertised price is before sales tax, and tax is added to the discounted amount at checkout. So the number you pay isn't the sale price — it's the sale price plus tax. The calculator lets you add your local rate to see the real out-the-door figure, which is the one that leaves your account.

Spotting a fake sale

A percentage is only meaningful against a real starting price. "Was $99, now $79" means nothing if the item was never actually sold at $99 — and some retailers raise the "original" price shortly before a sale so the discount looks larger. Judge a deal by the final price against what you'd happily pay, not by the size of the percentage on the sign. A big number off an inflated price can still be a bad deal.

Frequently asked questions

Do two discounts ever add up to their sum?

No. Because the second is taken from the already-reduced price, stacked percentages always combine to less than their total. The only way to get "50% off" is a single 50% cut.

Which is better: one big discount or two smaller ones?

Compare the effective rates. A single 45% beats a stacked 30%+20% (which is 44%). The order of two stacked discounts, interestingly, doesn't change the final price — 30% then 20% equals 20% then 30%.

Is anything uploaded when I use the calculator?

No. It all runs in your browser — nothing you enter is sent anywhere.