Start with the decision
Start with the same selling price, currency and landed product cost in both scenarios. Then separate costs that actually change: fulfillment, inbound allocation, storage, postage and packing labor. A comparison becomes misleading if one side includes labor and the other omits it.
Worked calculation
At price 30, referral assumption 15% and landed cost 10, 15.50 remains before fulfillment. FBA 5, inbound 1 and storage 0.50 leave 9.00. FBM postage 6 and packing labor 1 leave 8.50. These costs are examples, not Amazon rates.
Compare fulfillment on the same unit basis
For each fulfillment route, start from the same selling price and subtract the referral assumption, landed product cost and route-specific fulfillment, inbound, storage or dispatch costs. The comparison is only as complete as the inputs; record exclusions alongside the result.
Make a two-column comparison with the same SKU, sale price, currency, landed cost and expected return allowance. Put fulfillment-specific costs in separate rows so a lower estimate is explainable. Include labor on the merchant-fulfilled side when you pack and dispatch orders yourself; include inbound and storage allocations on the FBA side when applicable.
Check the changed-cost scenario
Use a recent fee estimate for the exact product dimensions and category, then replace it with actual statements as they arrive. Compare more than one selling price and a slower-sales case for inventory costs. A simple calculator helps organize assumptions; it cannot decide which fulfillment method will win in search or reliably estimate sales.
| Input or result | Value |
|---|---|
| Price / referral assumption | 30 / 15% |
| Landed cost | 10 |
| FBA fulfillment / inbound / storage | 5 / 1 / 0.50 |
| FBM postage / packing labor | 6 / 1 |
| FBA / FBM contribution | 9 / 8.50 |
If storage allocation grows from 0.50 to 2, FBA contribution drops to 7.50 with all other rows fixed. That reverses this illustrative comparison. It is not a prediction of which channel sells more units; obtain actual category costs first.
Use the example with your own inputs
Get applicable fees from Amazon for the product and category. Referral minima, tiers, inventory surcharges and return behavior are not automatically looked up in PourMargin.
Amazon FBA vs FBM Profit Calculator | PourMarginScope and source checks
These are planning examples, not actual seller results. Keep currency, tax basis and cost allocation consistent. Enter your own figures and reconcile with your records; tax, demand, refunds and unlisted business costs can change the outcome.
Source: Amazon fee and cost estimates. This article uses illustrative manual costs, not current category fee quotes.