Discount Calculator — Sale Price, % Off & Stacked Discounts

Enter the original price and the discount, and see the sale price and your saving instantly. Add your local sales tax to see the figure that will actually appear at the till, since tax is charged on the discounted price.

There's a dedicated mode for the offer that fools nearly everyone — "25% off, plus an extra 10% at checkout" — and a reverse mode that tells you what percentage off a marked-down price actually represents.

How to use Discount Calculator

Pick a mode. A straight percentage off, two stacked discounts, or "what % off is this sale price?".
Enter the prices and percentages. Results update as you type — no submit button.
Optionally add sales tax to see the real checkout figure.
Copy the result if you want to keep or share it.

Why 25% + 10% is not 35% off

Stacked discounts compound: the second percentage is taken off the already reduced price, not the original. On a 100 item, 25% off leaves 75, and 10% off that leaves 67.50 — a combined discount of 32.5%, not 35%. Retailers know the bigger-sounding number does the advertising, which is exactly why offers are worded this way. The stacked mode here shows the true combined percentage so you can compare offers honestly.

Percentage off vs amount off

"20% off" and "20 off" are different claims, and which is better depends entirely on the price. On an 80 item, 20% off saves 16 — the flat 20 is better. On a 200 item, 20% saves 40. The break-even is where the price equals the flat amount divided by the percentage: below it take the flat discount, above it take the percentage.

Is the discount even real?

A discount is only as honest as the "original" price. Before a big sale, check what the item actually sold for — price-history tools exist for the big retailers — because a "was" price that nothing ever sold at makes any percentage meaningless. A genuine 20% off a real price beats a fictional 60% off an inflated one.

Related tools

For a general-purpose version of these calculations, see the percentage calculator. If you're working out prices that include tax, the VAT calculator adds or removes it correctly.

Frequently asked questions

How do I work out 20% off a price in my head?

Take 10% (move the decimal point one place left) and double it. 20% off 85: 10% is 8.50, doubled is 17, so you pay 68. The same trick builds any percentage: 5% is half of 10%, 15% is 10% plus half again.

Why isn't 25% off plus 10% off the same as 35% off?

Because the second discount applies to the already-reduced price. 100 → 25% off → 75 → 10% off → 67.50. That's 32.5% off overall, not 35%. The gap grows with bigger percentages — 50% + 50% is 75% off, not free.

Is sales tax charged on the price before or after the discount?

After. Tax is charged on what you actually pay, so a discount reduces the tax too. That's why this calculator applies your tax rate to the discounted price — it matches what the till will do.

Which is better: 20% off or $20 off?

It depends on the price. They're equal when the price is $100 (since 20% of 100 is 20). Below $100 the flat $20 saves you more; above it the percentage wins. Divide the flat amount by the percentage to find your own break-even.

How do I find what percent off a sale price is?

Use the "What % off is it?" mode: it computes (original − sale) ÷ original × 100. From 80 to 60 is a 25% discount. It also tells you if the "sale" price is actually higher than the original — which happens more often than you'd hope.