Calculate SimplyHow to use
Start with the worked example to understand the inputs, then replace every relevant value with your own figures. Use one currency and consistent units throughout. Add or remove rows where offered; irrelevant conditional fields are disabled and excluded. Select Calculate after editing. Review negative values and any “not determined” result rather than assuming every scenario must be profitable. Download a text summary or print the page for your records.
Formula and assumptions
Reseller profit subtracts purchase cost, outbound shipping, packaging and fees from total buyer payment. Percentage fees apply to item price plus shipping charged to the buyer. Break-even item price solves that same equation for zero profit; it does not mean the item is likely to sell. ROI uses the purchase cost only, whereas profit margin uses total buyer payment. Zero purchase cost leaves ROI undefined. Use actual marketplace rates and allow separately for refunds, tax and unsold inventory when making a buying decision.
profit = (selling price + shipping charged) × (1 − fee rate) − purchase − shipping − packaging − fixed fees; ROI = profit / purchase × 100
Worked example
Example only: replace rates with your own figures.
Inputs
- Purchase cost: 20
- Expected item selling price: 50
- Shipping charged to buyer: 5
- Seller-paid shipping per item: 6
- Packaging cost per item: 1
- Percentage fees on total buyer payment: 13 %
- Fixed fees per sale: 0.3
- Net profit: 20.55 USD
- ROI on purchase cost: 102.75 %
- Profit margin on buyer payment: 37.3636 %
- Break-even item price: 26.3793 USD
- Total selling fees: 7.45 USD
Frequently asked questions
Are the example rates current market prices?
No. Example inputs demonstrate arithmetic, not live prices, tax rules, salary surveys or sponsor benchmarks. Enter a dated quote, bill, manufacturer specification or verified fee schedule that applies to your situation. Compare a conservative and an optimistic scenario separately.
Why is a result not determined?
Some calculations have no meaningful value when a denominator is zero, savings are non-positive, a target cannot be reached or your data do not bracket an intersection. The tool leaves that result undetermined instead of displaying infinity or inventing a recommendation. Check the method and your inputs.
Sources
Sources explain the underlying concepts, not an endorsement of this website or its results. Method review: 20 October 2026.