Why don't two 20% discounts equal 40% off?

Because the second 20% applies to the already-discounted price, not the original. $100 → 20% off → $80 → 20% off → $64. Total savings: $36, which is 36% off — not 40%. The effective discount is always less than the sum of the percentages (unless one of them is 0%).

Does order matter for stacked discounts?

For two pure percentage discounts, no — they multiply commutatively. But mixing percentages with fixed amounts makes order matter: $5 off then 20% off $100 = ($100 − $5) × 0.8 = $76. 20% off then $5 off = $100 × 0.8 − $5 = $75. The customer saves $1 more when the percentage comes second.

What happens if discounts exceed the price?

The subtotal never goes below $0 — any discount that would push it negative is clamped to bring the subtotal to exactly $0. The remaining discount value is lost (no store-credit carryover is modelled).

Can I model buy-one-get-one (BOGO) offers?

Not directly — BOGO is a quantity-based offer, not a price-stack. Approximate BOGO-50% by adding a 25% discount on a 2-unit basket (since one unit at full price + one at half = 1.5 ÷ 2 = 75% of full price, a 25% blended discount).

E-commerce Tools

Discount Stack Calculator

Stack any combination of percentage and fixed-amount discounts in the order they apply, and see exactly what the customer pays after each step. Add a 20% loyalty discount, then a 10% newsletter code, then a $5 refer-a-friend credit — the calculator walks through each discount against the running subtotal and reports the final price plus the effective combined discount percentage.

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How to use

1
Enter the original price
The full undiscounted price of the product or basket. All subsequent discounts apply to the running subtotal.
2
Add discounts in the order they apply
Each discount can be a percentage or a fixed amount. Order matters when mixing percent and fixed discounts — reorder with the up/down arrows to compare scenarios.
3
Read the step-by-step breakdown
Each step shows the amount subtracted, the price after the discount and the cumulative savings so far. The final price is highlighted at the bottom of the list.
4
Compare to a flat discount
The effective discount percentage shows what single flat discount would produce the same final price — useful for sanity-checking promo combinations.

Common use cases

Model a Black Friday stack: 30% site-wide + extra 15% with code BLACK15 + $10 email signup credit.
Verify that two stacked 20% discounts yield 36% off, not 40% — important for finance margin checks.
Calculate the effective discount when a fixed-dollar promo (e.g. $25 gift card) combines with a percentage sale.
Compare different discount orderings (percent-then-fixed vs fixed-then-percent) to find the most customer-friendly stack.

Limitations

Marketplace and payment-processor fee schedules change frequently. The rates embedded in this calculator are illustrative and were last reviewed in early 2025 — always confirm the current fee schedule on the platform's seller documentation before pricing decisions.
Discounts apply strictly in the listed order. With pure percentage discounts order doesn't matter (multiplication is commutative), but with a mix of percent and fixed it does — a $5 off applied first reduces the base for a subsequent 20%, while 20% first reduces the base for the $5.
The running subtotal never goes below $0 — any discount amount that exceeds the remaining subtotal is clamped to the running total. A $100 fixed discount on a $50 item applies $50 (not $100, no store-credit carryover).
This tool calculates the customer-facing price only — it does not deduct seller-side marketplace fees, payment processing, COGS or shipping. Use the Shopify / Etsy / eBay calculators for net profit on the discounted price.
Tax is not modelled. In most US jurisdictions discounts are applied before tax, so the tax base equals the final price after discounts — run the final price through a sales tax calculator separately.

Frequently asked questions

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Loading Discount Stack Calculator…

Discount Stack Calculator

How to use

Enter the original price

The full undiscounted price of the product or basket. All subsequent discounts apply to the running subtotal.

Add discounts in the order they apply

Each discount can be a percentage or a fixed amount. Order matters when mixing percent and fixed discounts — reorder with the up/down arrows to compare scenarios.

Read the step-by-step breakdown

Each step shows the amount subtracted, the price after the discount and the cumulative savings so far. The final price is highlighted at the bottom of the list.

Compare to a flat discount

The effective discount percentage shows what single flat discount would produce the same final price — useful for sanity-checking promo combinations.

Common use cases

Model a Black Friday stack: 30% site-wide + extra 15% with code BLACK15 + $10 email signup credit.

Verify that two stacked 20% discounts yield 36% off, not 40% — important for finance margin checks.

Calculate the effective discount when a fixed-dollar promo (e.g. $25 gift card) combines with a percentage sale.

Compare different discount orderings (percent-then-fixed vs fixed-then-percent) to find the most customer-friendly stack.

Limitations

Marketplace and payment-processor fee schedules change frequently. The rates embedded in this calculator are illustrative and were last reviewed in early 2025 — always confirm the current fee schedule on the platform's seller documentation before pricing decisions.
Discounts apply strictly in the listed order. With pure percentage discounts order doesn't matter (multiplication is commutative), but with a mix of percent and fixed it does — a $5 off applied first reduces the base for a subsequent 20%, while 20% first reduces the base for the $5.
The running subtotal never goes below $0 — any discount amount that exceeds the remaining subtotal is clamped to the running total. A $100 fixed discount on a $50 item applies $50 (not $100, no store-credit carryover).
This tool calculates the customer-facing price only — it does not deduct seller-side marketplace fees, payment processing, COGS or shipping. Use the Shopify / Etsy / eBay calculators for net profit on the discounted price.
Tax is not modelled. In most US jurisdictions discounts are applied before tax, so the tax base equals the final price after discounts — run the final price through a sales tax calculator separately.