What differs between the two
- FBA adds Amazon’s fulfilment fee, storage and your cost of sending stock to the warehouse and prepping it. Referral fee and plan fee are the same.
- FBM replaces those with your own packing and shipping, and lets you charge the buyer for shipping if you choose.
- Prices can differ: FBA listings qualify for Prime and often sell at a higher price or win more orders, so the calculator takes a separate price for each.
A worked example
A $30.00 item with a $8.00 product cost earns $6.80 per unit with FBA ($5.00 fulfilment, $0.20 storage, $1.00 inbound and $0.50 prep) and $7.00 with FBM when shipping yourself costs $6.50. FBA comes out -$0.20 ahead per unit; over 100 units that is -$20.00 a month.
The break-even point
The calculator also shows the FBA fulfilment fee at which both ways earn the same, and the FBM shipping cost at which they tie. These are more useful than a single verdict: FBA wins while its fee stays below the first figure, and FBM wins while your shipping stays below the second.
What the numbers cannot tell you
- Sales you win or lose through Prime. A Prime badge can lift conversion, which is not modelled here.
- Account-level and seasonal FBA charges, such as long-term storage, which depend on how long stock sits.
- Your time. FBM means packing and handling every order yourself.
Frequently asked questions
Is FBA always more profitable than FBM?
No. For heavy or oversized items, or slow sellers with high storage costs, FBM can win. For small, light and fast-moving items FBA often wins, especially if Prime lifts your price or sales.
Where do I get my FBA fee?
From Amazon’s Revenue Calculator, which uses your product’s size and weight. Enter it in the FBA fulfilment fee field.
Why can I enter two prices?
Because FBA and FBM listings often sell at different prices. Setting the same price on both compares like for like.
What do the break-even figures mean?
The break-even FBA fee is the highest fulfilment fee at which FBA still earns as much as FBM. The break-even FBM shipping cost is the highest shipping cost at which FBM still earns as much as FBA.
Does it include Prime or storage limits?
No. It compares per-unit economics with the costs you enter. Prime’s effect on sales and long-term storage surcharges are outside the calculation.