Double Discount Calculator
Stack two discounts back-to-back — see the real combined saving.
Calculator
100.00 × (1 − 20.00/100) × (1 − 10.00/100) = 72.00
How it works
Stacked discounts are everywhere — a department store puts a sweater on sale at 30% off, then your loyalty programme or a promo code knocks an extra 20% off the sale price; an online retailer offers 40% off site-wide and a 15% credit-card rebate at checkout; a clearance section discounts the original tag by half and then halves the sale price again on the last weekend of the season. People assume that stacking 30% and 20% means 50% off the original. It does not. The second discount applies to the already-reduced price, so the true effective discount is 44% off — meaningfully less than the 50% headline. This calculator removes the guesswork. Enter the original price and the two discount percentages and see four numbers: the price after the first discount, the price after the second, the total amount saved, and the real combined percent off. Like the rest of Nulumia, the maths happens in your browser; nothing is logged, nothing is shared, and every result is encoded in a shareable URL. Use it to negotiate with a salesperson who claims a stacked deal is bigger than it really is, to compare two offers where one is a single big discount and one is two smaller ones, or simply to set realistic expectations before you reach the till. The formula we use is the standard sequential-discount formula taught in every introductory algebra class — the FAQ below cites the source and walks through a worked example. Save the link, send it to whoever needs to see it, and check our work whenever you want.
Why use this calculator?
- Honest math. Shows the real effective discount, not the misleading sum of the two percentages.
- Private. Inputs never leave your browser. No analytics, no tracking, no signups.
- Shareable. The URL encodes every input. Send the link and the recipient sees the same result.
- Instant. Updates as you type. No submit button required when JavaScript is enabled.
- Works without JavaScript. Form falls back to a server-rendered GET response.
FAQ
Why isn't 30% plus 20% equal to 50% off?
Because the second discount applies to the already-reduced price, not the original. After 30% off, you pay 70% of the original. The 20% then comes off that 70%, leaving 56% — which is 44% off the original, not 50%.
What is the formula for two stacked discounts?
Final price = original × (1 − pct1/100) × (1 − pct2/100). Effective discount = (1 − final/original) × 100. The order of the two discounts does not matter — multiplication is commutative.
Does the order of the discounts matter?
No. Mathematically, applying 30% then 20% gives the same final price as applying 20% then 30%. In some stores the cashier may apply discounts in a specific order for policy reasons, but the final number is identical.
Can I stack three or more discounts?
This calculator handles two discounts at a time. For three or more, calculate the first two, then run the result through the single percentage-off calculator with the third discount. We are evaluating a multi-discount variant for a future release.
What if one of the discounts is a fixed dollar amount, not a percent?
This calculator only handles percent-based discounts. For mixed percent and dollar-amount discounts, subtract the dollar amount first and then run the result through the percentage-off calculator.
Where does the stacked-discount formula come from?
It is the standard sequential-percent-decrease formula from introductory algebra. Khan Academy and OpenStax College Algebra both cover it under exponential and percentage change.