Double Discount Calculator
"30% off, then an extra 20% at checkout" is not 50% off — it is 44%, because the second discount applies to the already-reduced price. Retailers know most shoppers add the numbers, which is exactly why stacked discounts look juicier than they are. This calculator applies the discounts in order, shows the true combined percentage, and prices the deal honestly.
The flat-alternative field answers the question deal hunters actually face: is "30% + extra 20%" better than the competitor's flat 45%? Enter both offers and the verdict line tells you which one wins and by how many dollars — the math most coupon threads argue about for pages, settled in one glance.
How to use
- Enter the original price and the two stacked discounts — the true combined percentage and final price appear instantly.
- Type the flat single discount you're comparing against to get the verdict: stacked wins, flat wins, or identical.
- Share the result with one tap — the link carries your numbers so the group chat sees the same math.
Frequently asked questions
What is 30% off then 20% off combined?
44% off, not 50%. The second discount multiplies what remains: 0.70 × 0.80 = 0.56, so you pay 56% of the original price. The calculator shows this multiplication chain step by step so the number is never a guess.
Why isn't adding two discounts correct?
Because percentages apply to different bases. The 20% comes off the post-30% price, not the original — each extra discount is worth less than the last. A 30%+20% stack equals a flat 44%; the same stack advertised as "50% off" overstates it by 6 points.
Is a stacked discount ever better than one big discount?
Yes — 30% + 20% (true 44%) beats a flat 40%. But 30% + 10% (true 37%) loses to a flat 40%. The comparison depends entirely on the numbers, which is why the verdict field exists: enter both offers and it names the winner in dollars.
Does this work for three or more discounts?
Keep multiplying: each discount leaves (100% − discount) of the price, so chain them — 0.9 × 0.8 × 0.7 for a 10%+20%+30% stack (true 49.6%). For the common two-discount case this page does the whole chain, the comparison and the share link for you.