{
    "name": "Marketplace Promotion ROI Calculator",
    "url": "https://calculators.geekmidst.com/calculators/marketplace-promotion-roi-calculator",
    "markdown": "https://calculators.geekmidst.com/calculators/marketplace-promotion-roi-calculator.md",
    "category": "Commerce & retail",
    "description": "Compare profit with and without a marketplace deal: discounted margin, extra units, promotion fees and ad spend, incremental profit, ROI and break-even units.",
    "summary": "A promotion pays off only if the extra units at a lower margin earn more than you would have made anyway at full price, after the deal fee and ad spend.",
    "also_called": [
        "Deal ROI calculator",
        "Promotion profitability calculator"
    ],
    "applies_to": "Worldwide",
    "last_updated": "2026-10-29",
    "computation": "Results are computed in the visitor’s browser on the HTML page. This API describes the calculator; it does not compute results.",
    "inputs": [
        {
            "name": "price",
            "label": "Regular selling price",
            "type": "number",
            "default": "40"
        },
        {
            "name": "discount_pct",
            "label": "Promotion discount",
            "type": "number",
            "default": "20",
            "unit": "%"
        },
        {
            "name": "unit_cost",
            "label": "Cost per unit (product + fulfilment)",
            "type": "number",
            "default": "18"
        },
        {
            "name": "fee_pct",
            "label": "Marketplace fee on the selling price",
            "type": "number",
            "default": "15",
            "unit": "%"
        },
        {
            "name": "baseline_units",
            "label": "Units you would sell without the deal",
            "type": "number",
            "default": "100"
        },
        {
            "name": "promo_units",
            "label": "Units sold during the deal",
            "type": "number",
            "default": "260"
        },
        {
            "name": "promo_spend",
            "label": "Deal fee and ad spend",
            "type": "number",
            "default": "500",
            "optional": true
        },
        {
            "name": "currency",
            "label": "Currency",
            "type": "currency",
            "default": "USD"
        }
    ],
    "outputs": [
        {
            "key": "incremental_profit",
            "label": "Extra profit from the deal",
            "format": "currency"
        },
        {
            "key": "roi",
            "label": "ROI on deal cost",
            "format": "percent"
        },
        {
            "key": "break_even_units",
            "label": "Units needed to break even",
            "format": "text"
        },
        {
            "key": "promo_price",
            "label": "Deal price",
            "format": "currency"
        },
        {
            "key": "promo_margin",
            "label": "Profit per unit at deal price",
            "format": "currency"
        },
        {
            "key": "baseline_profit",
            "label": "Profit without the deal",
            "format": "currency"
        },
        {
            "key": "promo_profit",
            "label": "Profit with the deal",
            "format": "currency"
        },
        {
            "key": "promo_cost",
            "label": "Deal cost (discount given + spend)",
            "format": "currency"
        }
    ],
    "formula": {
        "text": "Unit profit = Price × (1 − Fee%) − Cost;  Extra profit = Deal units × Deal unit profit − Spend − Baseline units × Regular unit profit;  ROI = Extra profit ÷ (Spend + Deal units × Discount per unit)",
        "variables": {
            "Baseline units": "what you would have sold at full price in the same period",
            "Spend": "deal fee, coupon fees and advertising for the promotion"
        }
    },
    "worked_example": {
        "inputs": {
            "price": "40",
            "discount_pct": "20",
            "unit_cost": "18",
            "fee_pct": "15",
            "baseline_units": "100",
            "promo_units": "260",
            "promo_spend": "500",
            "currency": "USD"
        },
        "steps": [
            "Regular unit profit = 40 × 0.85 − 18 = 16, so 100 units = 1,600.",
            "Deal price 32; unit profit = 32 × 0.85 − 18 = 9.20; 260 × 9.20 − 500 = 1,892.",
            "Extra profit = 1,892 − 1,600 = 292; deal cost = 500 + 260 × 8 = 2,580; ROI = 11.32%.",
            "Break-even = (1,600 + 500) ÷ 9.20 = 228.3, so 229 units."
        ],
        "result": "The deal earned 292 more than selling at full price, an 11.3% return on its cost; it needed 229 units to break even."
    },
    "interpretation": "Extra profit is the number that matters; revenue and units always look good during a deal. Any later lift from better ranking or reviews is a bonus not counted here, and any sales pulled forward from next month are a cost not counted here.",
    "assumptions": [
        "The marketplace fee is a percentage of the selling price.",
        "Unit cost is the same with and without the deal."
    ],
    "limitations": [
        "Halo effects on other products, post-deal ranking changes and pulled-forward demand are not modelled."
    ],
    "rules": null,
    "faqs": [
        {
            "question": "How do I estimate baseline units?",
            "answer": "Use sales of the same product in a comparable period without a promotion, adjusted for seasonality."
        },
        {
            "question": "Why is ROI low even though sales tripled?",
            "answer": "Because each discounted unit earns much less, and you also gave the discount to customers who would have bought anyway."
        }
    ],
    "sources": [],
    "related": [
        {
            "name": "ROAS Calculator",
            "url": "https://calculators.geekmidst.com/calculators/roas-calculator"
        },
        {
            "name": "ROI Calculator",
            "url": "https://calculators.geekmidst.com/calculators/roi-calculator"
        },
        {
            "name": "Discount Calculator",
            "url": "https://calculators.geekmidst.com/calculators/discount-calculator"
        },
        {
            "name": "Break-even Calculator",
            "url": "https://calculators.geekmidst.com/calculators/break-even-calculator"
        }
    ],
    "disclaimer": null,
    "publisher": "GM¹X CalcVerse"
}