Final Price After Discount Calculator

Behind the number

Final price after a single discount is original × (1 − discount). After several sequential discounts it is original × (1 − d₁) × (1 − d₂) × (1 − d₃), because each applies to the price left by the one before.

Adding the discounts and applying the total gives a lower price than stacking them, and the difference grows with the number of discounts. Twenty, ten and five percent stacked is 31.6%, not 35%.

A real example

A $58 item with 20% off, then a 10% code, then a further 5% loyalty discount.

Stacked: 58 × 0.8 × 0.9 × 0.95 = $39.67. Added: 58 × 0.65 = $37.70. The stacked price is $1.97 higher, which is 3.4% of the original.

Now check the floor. At $26.10 of cost, $39.67 leaves $13.57 of contribution before fulfilment. Adding $6.40 of per-order cost leaves $7.17. The stack has survived; a fourth discount of 15% would take it to $33.72 and leave $1.22, which is effectively nothing.

The usual mistakes

Order of application does not change the final price, multiplication is commutative, but it does change how the saving is presented. Customers perceive a large discount followed by a small one as more generous than the reverse, despite an identical result.

Whether tax applies before or after the discount does change the total, and it varies by jurisdiction and by what is being discounted. On a taxable sale the discount normally reduces the taxable base, which means the customer saves the tax on the discount too.

Using the result

Set a hard price floor in the platform, calculated per product from actual variable cost. Stacked discounts taking a price below cost is the single most common unintended pricing failure, and it happens at the busiest moments when nobody is checking.

Then decide deliberately which discounts may combine. Most platforms allow codes to stack with sale prices by default, and most businesses have never chosen that setting.

The exclusion rules worth setting

Three exclusions cover nearly every problem. Codes do not apply to already-discounted items. Codes do not stack with each other. And a global floor prevents any combination from taking a price below the calculated minimum.

The first two are policy and are visible to customers, which means they have to be stated clearly at checkout rather than discovered when a code fails. A code that silently does not work costs the order; one that explains why does not.

The third is a safety net that should never be reached. If it is being hit regularly, the discount structure above it is wrong, and the floor is masking a problem rather than solving one, which is worth checking rather than being reassured by.

It is worth showing the full stack at checkout rather than a single combined figure. A customer who sees the sale saving, the code saving and the loyalty saving as separate lines perceives more value from the same total than one who sees a single discount, and the transparency prevents the support queries that a mysterious total generates.

The one exception is where the stack is small. Three discounts totalling four percent listed line by line reads as fussy rather than generous, and a single line serves better.