Amazon FBA vs FBM UK (2026): which should you use?

When you sell on Amazon, you choose who does the shipping: Amazon (FBA) or you (FBM). It's one of the first real decisions a UK seller makes, and it changes your costs, your workload and your Prime eligibility. Here's the honest comparison and how to pick.

What each one means

• FBA — your stock lives in Amazon's fulfilment centres. When an order comes in, Amazon picks, packs and ships it, usually with Prime delivery, and handles most customer service and returns. You pay a per-unit fulfilment fee plus storage. (New to it? See how Amazon FBA works.)
• FBM — your stock stays with you. When an order comes in, you pack and ship it and handle service and returns. No per-unit FBA fee, but you own the logistics.

The trade-offs

When FBA is the right call

FBA suits most arbitrage sellers because:

• Prime lifts sales — many shoppers filter for Prime, and it builds trust.
• It scales — you're not packing boxes every day; you send stock in and move on.
• Buy Box edge — FBA offers are favoured, which matters on shared listings (see Buy Box explained).

The catch is fees: the per-unit fulfilment fee and storage fees have to leave room for profit. On thin-margin or bulky items they might not.

When FBM makes more sense

Choose FBM when FBA's fees would kill the deal:

• Large or heavy items — high FBA fulfilment fees; you may ship cheaper yourself.
• Slow sellers — avoid stacking storage and aged-inventory fees on stock that sits.
• Very low-margin items — where the per-unit FBA fee wipes out the profit.
• You want control — over packaging, dispatch and stock on hand.

Some sellers use both: FBA for fast, small items and FBM for bulky or slow ones.

How to decide per product

Don't pick one method for everything — decide per product by comparing profit under each. The free Axivelo FBA calculator lets you see net profit and ROI with FBA fees applied, and the Axivelo app defaults to FBA maths on a scan (with an FBM option in settings), so you can tell in seconds whether Amazon's fulfilment leaves enough margin or whether shipping it yourself is better. For the full fee picture, see Amazon FBA fees explained; if you're just starting, how to sell on Amazon UK covers the setup.

Compare the same ASIN under both methods

Suppose a product can sell at £24 through either route. FBA adds Amazon's per-unit fulfilment and storage charges plus your shipment to its warehouse. FBM substitutes your postage, packing materials, pick-and-pack time and responsibility for buyer messages and returns. The referral fee remains relevant under both. Do not compare a bare FBM postage label with an all-in FBA fee: write the complete cost line for each route, include VAT where applicable, and consider the delivery promise buyers actually see on the listing. A heavy, slow item can favour FBM, while a compact item with repeat sales may suit FBA; neither follows from size alone.

Amazon explicitly permits a mixed FBM and FBA catalogue. Use its fee and revenue estimator to compare the same listing and price under each method; then add your own true postage and storage assumptions. Check whether FBA restrictions, size tiers or peak charges apply to the precise SKU. Start with a small quantity, record the time and cash spent per order, and revisit the choice after you have actual sales instead of treating fulfilment as a permanent brand decision.

What the FBM price must pay for

FBM does not mean “no fulfilment fee” in the economic sense. You buy packaging, pick and pack each order, pay the carrier, supply tracking as required and meet the promised dispatch time. A heavier parcel can incur a charge beyond the label price you first see. You also manage seller-fulfilled returns and messages. If an item sits in your spare room instead of an FBA warehouse, storage is not necessarily free: space and the risk of damage still have an opportunity cost. FBM can give more control over handling and be sensible for awkward items, but only after these costs are written down.

FBA shifts picking, packing and delivery to Amazon. It can simplify orders at scale, but you pay to send inventory in, Amazon charges fulfilment and storage fees, and unsold stock may incur aged-inventory costs. Some goods cannot be sent under FBA rules or need special preparation. Amazon's FBA guide and FBM programme describe the current responsibilities. Neither fulfilment route removes the referral fee or product compliance requirements.

A practical comparison worksheet

1. Use one exact ASIN and record the same VAT-inclusive selling price for both routes.
2. Estimate referral fees for the item's real category, then use Amazon's current fulfilment estimate for FBA.
3. For FBA add prep, inbound shipping, storage, peak fees if applicable and expected returns.
4. For FBM add postage, packaging, labour, your storage and expected customer-service or return costs.
5. Compare estimated net profit per unit, cash tied up and time per order. Test the conclusion with a small batch.

If your FBM offer would need a lower sale price to compete with Prime offers, recalculate at that price. If your FBA shipment would arrive after a seasonal demand peak, the theoretical higher price may also be unavailable. These are offer-level decisions, not permanent labels attached to an ASIN.

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