Stacked discount calculator
A sale, then a coupon, then a member discount. Enter them in order and see what you really pay, step by step.
One after another
- Original price$80.00
- 120% off−$16.00$64.00
- 210% off−$6.40$57.60
One after another
$57.6028% off in totalIf the percentages were added
$56.0030% offWhy discounts don't simply add up
When a shop applies two discounts, the second is normally taken off the price left after the first, not off the original. A 20% sale followed by an extra 10% coupon takes 10% of the already reduced price.
Combined discount = 1 − (1 − first) × (1 − second) × …
Example: $80 with 20% off is $64. Another 10% off $64 is $6.40, leaving $57.60. That is 28% off in all, not 30%, because 1 − 0.8 × 0.9 = 0.28.
When the order matters
With percentages only, the order makes no difference. Add a fixed amount, like a $15 voucher, and it does: the percentage saves more when it is worked out on the bigger price, so percentage first and voucher last costs you less. The calculator applies discounts in the order you list them and tells you when another order would be cheaper.
Questions
Is 50% off plus another 50% off free?
No. The second 50% is half of what is left, so you pay a quarter of the original price: 75% off in total.
Do shops always apply discounts one after another?
Most do, but terms vary and some codes can't be combined at all. The "if added" figure is the best case; the receipt has the final word.
How many discounts can I stack here?
Up to five, each a percentage or a fixed amount. A fixed amount never takes the price below zero.