Discount calculator
See the discounted price and your savings, including a discount on a discount. Example: 30% then 20% is not 50% — the real cut is 44%.
How the calculation works
A single discount takes a percentage off the price: final = price × (1 − d). A R$100 item at 30% off costs 100 × 0.70 = R$70.
The tricky part is stacked discounts ("20% + 10%"). They do not add up — each applies to the price already reduced by the previous one:
final = price × (1 − d1) × (1 − d2)
Why 20% + 20% is not 40%
Price of R$100:
- First 20% off: 100 × 0.80 = R$80
- Second 20% off the R$80: 80 × 0.80 = R$64
You paid R$64, a 36% discount — not 40%.
Equivalent discount
The single discount equal to several stacked: 1 − (1 − d1)(1 − d2). For 20% and 20%: 1 − 0.64 = 0.36 = 36%.
Finding the original price
If an item sold for R$68 at 15% off, the full price was 68 ÷ 0.85 = R$80. Divide (don't multiply) by the discount factor.
Examples
- R$250 at 40% off: 250 × 0.60 = R$150.
- 30% + 10% stacked: 1 − 0.70 × 0.90 = 37% real discount, not 40%.
Frequently asked questions
Do two 10% discounts make 20%?
No. They apply in sequence, resulting in a 19% total discount (1 − 0.90 × 0.90).
Does the order of the discounts matter?
No. Since it is multiplication, 20% then 10% equals 10% then 20%. The final price is identical.
How to find the price before the discount?
Divide the discounted price by (1 − discount). R$90 at 25% off came from 90 ÷ 0.75 = R$120.
Is 30% then 20% off the same as 50%?
No. The second discount applies to the already-reduced price: 100 × 0.70 × 0.80 = 56, a real discount of 44%.
How do I find the original price from a discounted one?
Divide by the remaining factor. R$68 after 15% off: 68 ÷ 0.85 = R$80. Multiplying by 1.15 gives the wrong answer.
Margin versus markup?
Margin divides profit by the selling price; markup divides it by cost. A R$60 item sold at R$100 has a 40% margin and a 66.7% markup.
Cash discount or interest-free instalments?
Compare the discount with what your money would earn over the period. A 5% discount to avoid three instalments is a 5% gain in about two months.
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Updated on June 17, 2026 · by Rafael Rossi · Methodology & sources