Calculate sale prices, savings amount and discount percentage
A discount calculator works out the three numbers that matter when something is on sale: the final price after the discount, the amount you save, and — if you only know the original and sale prices — what percentage the discount actually is. "30% off £80" and "this dropped from £80 to £56 — what discount is that?" are the everyday questions it answers, turning a sale tag into a clear figure rather than mental arithmetic at the till.
The useful trick it makes easy is reversing the calculation: shops show a sale price, but the real question is often how big the discount truly is, or what the original price was before a stated reduction. It also handles stacking pitfalls — two successive discounts do not simply add up, because the second applies to the already-reduced price, so "20% then 10% off" is not 30% off. This tool computes all of it instantly in your browser, so you can check a deal in seconds.
Subtract the sale price from the original, divide by the original, and multiply by 100. So £80 down to £56 is (80−56) ÷ 80 × 100 = 30% off. The calculator does this directly when you enter both prices.
No — this is a common trap. A 20% then 10% discount is not 30% off, because the 10% applies to the already-reduced price. The combined effect is 28% off. Apply them in sequence rather than adding the percentages.
If an item is 25% off and now costs £60, the sale price is 75% of the original, so divide by 0.75 to get £80. Working backward from a discounted price requires dividing by (1 minus the discount), not adding the percentage back.
The core calculation is the discount itself. If tax is added after the discount, apply the discount first to get the reduced price, then add the tax on that lower amount — the order matters for the final total you pay.
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