How to use the discount calculator
- 1Choose Sale price, Percent off or Stacked discounts.
- 2Enter the Original price and the discount (or the sale price, for Percent off).
- 3Optionally add Sales tax or VAT to see the price at the till, and pick a Currency.
- 4Read what you pay and the saving, with the formula below. Press Copy result to copy it.
30% off, then 20% + 10% stacked
Original price 2,499 with 30% off Original price 100 with 20% then 10% off
You pay 1,749.30 (saving 749.70) You pay 72.00: an effective 28% off, not 30%
Sale price from a percentage
Multiply the original price by what's left after the discount:
- Sale price = Original × (1 − Discount ÷ 100)
- Saving = Original × Discount ÷ 100
25% off 80 is 80 × 0.75 = 60, a saving of 20. A quick mental check: 10% of a price is the price with the decimal point moved one place left (10% of 80 = 8), so 20% is double that and 5% is half.
Finding the discount percentage
When a tag shows only the old and new prices, the percent off is the saving divided by the original price:
- Percent off = (Original − Sale) ÷ Original × 100
A price cut from 1,200 to 900 is (1,200 − 900) ÷ 1,200 × 100 = 25% off. Always divide by the original price. Dividing by the sale price (300 ÷ 900 = 33%) answers a different question: how much more the full price is than the sale price.
Stacked (double) discounts
"20% off plus an extra 10%" means the second discount applies to the already-reduced price, so the percentages multiply rather than add:
- Final = Original × (1 − d₁ ÷ 100) × (1 − d₂ ÷ 100)
- Effective discount = 1 − (1 − d₁ ÷ 100) × (1 − d₂ ÷ 100)
20% then 10% gives 0.8 × 0.9 = 0.72 of the price: 28% off, not 30%. The order of the two discounts doesn't change the result. Stacked discounts accepts up to three.
Discount plus tax
Where sales tax or VAT is added at the till, it's normally charged on the discounted price, so the discount also reduces the tax. The calculator applies the optional tax rate after the discount:
- Price paid = Sale price × (1 + Tax ÷ 100)
In countries where shelf prices already include VAT or GST (the UK, the EU, India), leave the tax box empty: the discount is taken off the tax-inclusive price. To see the tax inside a price, use the GST calculator.
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