Discount Calculator
Flexible discount calculator for percent-off and fixed-amount discounts, stacked promos, cart quantity, and optional sales tax.
Percent off, 0–100.
Applied to the already-discounted price.
What this calculator does
This is the broader discount tool: it supports percent or fixed-amount discounts, an optional stacked second discount in either mode, a quantity for cart totals, and a sales tax add-on. For one-line shopping math (single item, single percent off) the lighter Percent Off Calculator may be quicker.
Formula
Percent discount: price = original × (1 − d ÷ 100)
Fixed discount: price = max(0, original − d)
Stacked: apply discount 1 to original, then discount 2 to the result.
Effective: (total savings ÷ original total) × 100
After tax: total = final × (1 + tax ÷ 100)
Variable definitions
original: Per-item price before any discount.d / d₂: Discount amounts, percent or fixed dollars depending on the mode.quantity: Number of identical items in the cart.tax: Sales tax rate as a percent, applied to the final discounted total.effective %: Total savings ÷ total original × 100, the single-percent equivalent.
Step-by-step calculation
- Apply the first discount to the original per-item price (percent or fixed).
- If stacked, apply the second discount to the already-reduced per-item price.
- Multiply by quantity to get the cart subtotal and total savings.
- Optionally apply sales tax to the cart subtotal for the out-the-door total.
Worked example
Three pairs of jeans at $80 each, with a 20% off promo, an extra $5 off stacked coupon, and 8% sales tax:
- After 20% off: 80 × 0.80 = $64.00
- After $5 stacked: 64 − 5 = $59.00 per item
- Per-item savings: 80 − 59 = $21.00 (effective 26.25% per item)
- Cart subtotal (×3): 59 × 3 = $177.00 · total savings $63.00
- After 8% tax: 177 × 1.08 = $191.16 out-the-door
How to use this calculator
- Enter the original per-item price and pick the first discount type (% or $).
- Enter the discount value. Toggle Stacked to add a second discount in either mode.
- Set quantity for cart totals. Add a sales tax % for the after-tax total.
- Use Copy or Share to send the final price, savings, and effective discount together.
Common mistakes
- Adding stacked percents: 20% + 10% is 28% off, not 30%.
- Mixing fixed and percent without checking signs: a $20 fixed discount on a $10 item should not produce a negative price, the calculator floors at $0.
- Forgetting quantity: per-item savings are unchanged by quantity, but cart savings scale with it.
Frequently asked questions
›How is this different from the Percent Off calculator?
Percent Off is a quick single-discount tool for one item: original price, percent off, sale price. The Discount Calculator handles fixed-amount discounts, stacked discounts, quantity / cart totals, optional sales tax, and computes the effective discount across everything combined.
›How do stacked discounts work?
Stacked discounts apply one after the other, not added. A 20% coupon followed by a 10% coupon is 1 − (0.8 × 0.9) = 28% off the original, not 30%.
›What is the effective discount percentage?
Total savings divided by the original price, times 100. It tells you the single equivalent percent off after combining percentage discounts, fixed-amount discounts, and the cart quantity.
›Can I mix a percentage discount and a fixed-amount discount?
Yes. The first discount applies in its chosen mode (% or $), then the second discount applies in its own mode on the already-reduced price.
›Does the tax apply before or after the discount?
Tax is applied to the final discounted price, the standard practice in the U.S. Enter your local sales tax percentage to see the out-the-door total.
›How does quantity affect the result?
The per-item original and per-item final price are used; total savings and total cost scale by quantity. Per-item savings stays constant regardless of quantity.
›Why is the effective discount different from the sum of the two discounts?
Because stacking is multiplicative for percent discounts, and because a fixed dollar discount on top of a percent discount shifts the effective rate depending on the price.
Related calculators
If this helped, the following calculators are useful for quick everyday math:
- Percent Off CalculatorSale price and savings after a discount.
- Percentage CalculatorX% of Y, X is what % of Y, X is Y% of what.
- Percentage Increase CalculatorPercent growth from original to new value.
- Percentage Decrease CalculatorPercent drop from original to new value.
- Percentage Difference CalculatorSymmetric % difference between two values.
- Tip CalculatorCalculate gratuity, total, and per-person share.