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Guide · Pricing & Margin

Stacked Discounts: Multiply the Remaining Prices

Calculate sequential discounts, coupon ordering, and the final contribution without adding percentages that use different price bases.

By PriceAndProfit Editorial Updated 3 min read

On this page
  1. Worked calculation
  2. Decision checks and limits
  3. Apply the calculation

Sequential percentage discounts apply to a changing base. A 20% reduction followed by a 10% reduction usually means paying 80% of list price and then 90% of that reduced amount. The total price factor is 0.80 × 0.90 = 0.72, giving a 28% effective discount from list price. Adding the advertised rates to claim a 30% discount would use the wrong denominator for the second reduction.

Worked calculation

Final price = list price × (1 − first discount) × (1 − second discount); effective discount = 1 − final price ÷ list price

For an item listed at $150, a 20% promotion reduces price to $120. A further 10% coupon removes $12, not $15, and produces a $108 final price. If the item's variable cost is $72, contribution is $36. That is a 33.3333% contribution margin on the final $108 sale. The discount percentage is based on the original $150 list price, while the contribution margin is based on the customer's final price.

Two percentage reductions commute mathematically when they apply to the same eligible items and there are no intermediate rounding or eligibility rules. Applying 10% and then 20% also gives $108 here. A fixed-dollar coupon changes the ordering. After 20% off, a $10 coupon gives $110. Subtracting $10 first and then taking 20% off gives $112. A checkout policy must state which sequence applies rather than leaving staff to infer it.

Hypothetical worked example
Sequence on $150 list priceFinal priceEffective discount
20%, then 10% $108.00 28%
20%, then $10 $110.00 26.6667%
$10, then 20% $112.00 25.3333%

Decision checks and limits

Order-level thresholds introduce another dependency. A coupon may require a minimum subtotal before or after other discounts, and some products may be ineligible. Calculate the eligible base separately from the displayed cart total. If shipping is excluded from the promotion but a selling fee is charged on shipping receipts, neither percentage should automatically use the same base. The correct calculation follows the actual offer and agreement.

Keep sufficient precision through the discount sequence, then reproduce the store's documented line-item or order-total rounding rule. For baskets with several quantities, rounding each unit can differ from rounding each line or the final cart. Review both the customer's payable total and the contribution after all variable costs. A valid marketing discount calculation can still produce an unprofitable order. Discounts outside the allowed zero-to-100% range or fixed coupons exceeding the eligible price require an explicit policy; do not silently turn an over-discounted negative price into zero in the analytical model.

Apply the calculation

  1. List eligible bases

    Document which products, shipping amounts, and subtotals each discount applies to before multiplying rates.

  2. Reproduce checkout order

    Apply percentages and dollar coupons in the stated sequence, including eligibility checks and the actual rounding rule.

  3. Audit retained contribution

    Subtract the costs of every included product and order-level expense from final revenue, then compare with the intended contribution floor.

Method references: OpenStax: Contribution margin. Accessed October 22, 2026. All dollar figures are hypothetical worked examples.

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