Discount Calculator (sale price and savings)

Find the sale price after a percentage discount, how much you save, and the effect of stacking a second discount on top.

Sale price–

You save–

Effective total discount–

You pay (% of original)–

Working out a discount

A percentage discount takes that share off the original price. The saving is the percentage of the price, and what's left is what you pay.

saving = price × d/100 · sale price = price × (1 − d/100)

The quick way

Rather than working out the discount and subtracting, go straight to what you pay: 25% off means paying 75%, so multiply by 0.75. One step instead of two, and much easier to do mentally — 30% off is ×0.7, 40% off is ×0.6.

Stacked discounts don't add up

This is the trap worth knowing. "25% off, then an extra 20% off at the till" is not 45% off. The second discount applies to the already-reduced price, so you pay 0.75 × 0.80 = 0.60 of the original — a 40% total discount, not 45. Stacked discounts always come out less generous than they sound, and the gap widens the bigger the individual percentages.

Worked example

An 80 item at 25% off saves 20, so the sale price is 60. Add a further 20% off and you pay 60 × 0.80 = 48 — a total saving of 32, which is 40% of the original, exactly as the stacking maths predicts.

For the general percentage arithmetic behind this, see thepercentage calculator; to add or strip sales tax from the result, use the VAT calculator.

Stacked discounts do not add up

Two successive discounts are not the sum of the two. 20% off then a further 10% off is not 30% off — the second applies to the already-reduced price, giving 28%. The order does not matter to the result, but the arithmetic never reaches the naive total. Watch also whether a discount applies before or after tax, which changes the final figure and is set by local rules rather than by the retailer.