Double Discount Calculator
Stacks a second percent-off deal on top of the first and shows the honest combined discount and final price — which is always less than the two rates added together.
How it works
When two discounts stack, the second one only cuts into what's left after the first. Start at $100, take 20 percent off to reach $80, then take an extra 15 percent off that $80 — you land at $68, not $65. That's a true 32 percent discount, not the 35 you'd guess by adding.
The reason the numbers never simply add is that each cut works on a smaller base. The bigger your discounts, the wider the gap between the naive sum and reality: two 50-percent cuts feel like 100 percent off but actually leave you paying a quarter of the original.
The tool shows the price after the first cut, the real combined percentage, the total dollars saved, and the final price — plus a reminder of what the misleading added-up number would have been so you can see the difference at a glance.
Frequently asked questions
Why isn't 20% then 15% equal to 35% off?
Because the 15 percent comes off the already-reduced price, not the original. Twenty percent off leaves 80 percent; fifteen percent off that leaves 85 percent of the 80 — which works out to 68 percent of the start, so 32 percent off in total.
Does the order of the two discounts matter?
No. Multiplying 0.80 by 0.85 gives the same result as 0.85 by 0.80, so applying the bigger or smaller discount first lands on the identical final price. The combined percentage is the same either way.
How do I find the true combined discount myself?
Convert each to what's left — 20 percent off is 0.80, 15 percent off is 0.85 — multiply them (0.68), then subtract from 1. That 0.32 means 32 percent off combined. The calculator runs this for you automatically.