Overview
A discount calculator that handles both a single markdown and stacked 'extra 20% off' promotions, showing the final price, the total saved, and the true effective discount. It exists chiefly to correct the common intuition that a 30% discount followed by a 20% discount equals 50% off.
How It Works
Enter the original price, set the first discount on a slider from 0 to 90 percent, and optionally add a second, stacked discount from 0 to 50 percent. The outputs show the price after the first discount, the final price, the amount saved overall, the effective discount as a percentage of the original price, and the stacked multiplier — the fraction of the original price you actually end up paying.
Step-by-Step Usage Guide
- Enter the original ticket price.
- Set the first discount percentage.
- Add a second stacked discount if the promotion has one.
- Compare the effective discount with the headline percentages to see the real deal.
Technical Specifications & Standards
Stacked discounts are multiplicative, not additive: the code computes final = price × (1 − d1) × (1 − d2). A 249.99 item at 30% off plus an extra 20% costs 249.99 × 0.70 × 0.80 = 139.99, an effective discount of 44%, not 50% — because the second percentage applies to the already-reduced price. The 'stacked multiplier' output shows that product directly (0.56 of original in this example), which is the number retailers' fine print implicitly relies on. Two boundary behaviours are worth knowing: the effective-discount figure divides by the original price with a small floor to avoid division by zero, and percentages are applied to the plain price with no tax involvement, so results describe pre-tax prices. The sliders cap at 90 and 50 percent respectively to keep inputs in realistic promotional ranges. When comparing two stores' promotions, compare final prices or the effective-discount figure, never the sum of headline percentages.
Targeted Use Cases
- Evaluating a '30% off plus extra 20%' sale before buying.
- Checking whether a bundled promotion beats a single straight discount.
- Setting a retail markdown ladder and predicting the shelf price.
- Explaining to a colleague why stacked coupons never add to their sum.
Notes & Gotchas
- Always read the effective-discount figure rather than adding the headline percentages.
- Model discounts in the order the store applies them; pure percentages commute, but mixed coupon types can differ.
- Remember results are pre-tax; VAT or sales tax applies to the discounted price.
- For a single discount, set the extra slider to 0 and read the final price directly.
Frequently Asked Questions
Is 30% off plus 20% off the same as 50% off?
No. Stacked discounts multiply: 0.70 × 0.80 = 0.56, so you pay 56% of the original — an effective discount of 44%. The tool shows this as the stacked multiplier so the gap is explicit.
Which price does the second discount apply to?
The already-discounted price, mirroring how stores apply successive promotions at the till. That is why the effective discount is smaller than the sum of the two percentages.
Does the calculator include tax?
No. All figures are on the pre-tax price you enter. Sales tax or VAT would be computed on the final discounted price by the checkout, not by this tool.
Can I model a fixed-amount coupon here?
Not directly — both inputs are percentages. Convert a fixed coupon into a percentage of the current price, or use the flat discount support on the invoice generator if you need amount-off arithmetic.