How the Triple Discount Calculator works
A "triple discount" (also called a stacked, chained, or successive discount) is what happens when three separate percentage-off deals apply one after another to the same price — a seasonal markdown, then a clearance discount, then a coupon, for example, or a chain of trade discounts a wholesaler quotes to a retailer. Each discount is taken off the price that remains after the previous one, not off the original price, so the discounts multiply rather than add.
The formula
For an original price P and three discount rates d1, d2, and d3 (each written as a decimal, so 20% is 0.20), the final price is:
Final Price = P × (1 − d1) × (1 − d2) × (1 − d3)
Total savings is simply the original price minus the final price. To compare a stacked discount against a single flat discount offer, the calculator also converts the three rates into an equivalent single discount: 1 − [(1 − d1) × (1 − d2) × (1 − d3)], expressed as a percentage.
Worked example
Take a $100 item marked down 20%, then a further 10% off the sale price, then a final 5% off at checkout. Step by step: $100 × 0.80 = $80.00, then $80.00 × 0.90 = $72.00, then $72.00 × 0.95 = $68.40. The final price is $68.40, total savings are $31.60, and the equivalent single discount is 1 − 0.684 = 31.6% — noticeably less than the 35% you'd get by simply adding 20% + 10% + 5%.
Why discounts don't add up
Adding percentage-off rates is the single most common mistake with stacked discounts. Each successive discount applies to an already-reduced balance, so its dollar value shrinks every time. The gap between the naive sum and the true equivalent discount grows with both the size of the rates and how many are stacked — with three moderate discounts the gap is often a few percentage points, and it gets larger as the rates increase.
Order doesn't change the final price
Because multiplication is commutative, (1 − d1) × (1 − d2) × (1 − d3) gives the same product no matter which discount is applied first, second, or third. Applying the 5% discount before the 20% discount produces the same final price and total savings as the reverse order — only the intermediate subtotals differ along the way. This is useful when comparing offers where a retailer or supplier lists discounts in a different order than you'd naturally apply them.
Where triple discounts show up
- Retail markdowns: a seasonal sale, an additional clearance percentage, and a final coupon or loyalty discount stacked at checkout.
- Trade discount chains: wholesalers and distributors often quote a chain like "20/10/5" instead of one flat rate, so buyers can compute the net price a supplier will actually invoice.
- Volume and early-payment terms: a bulk-purchase discount, a promotional discount, and an early-payment discount applied together on a single invoice.