Discount Calculator

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

1. Apply the first discount to the original per-item price (percent or fixed).
2. If stacked, apply the second discount to the already-reduced per-item price.
3. Multiply by quantity to get the cart subtotal and total savings.
4. 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

1. Enter the original per-item price and pick the first discount type (% or $).
2. Enter the discount value. Toggle Stacked to add a second discount in either mode.
3. Set quantity for cart totals. Add a sales tax % for the after-tax total.
4. 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