Amazon FBA: The Complete Guide

Fulfilment by Amazon (FBA) is one of the most significant decisions you’ll make as an Amazon seller. It determines whether Amazon handles your logistics or you manage everything yourself. This guide covers how FBA works, the fees involved, and whether it’s the right choice for your business.

How FBA Works

How Amazon FBA works

FBA operates on a straightforward principle: you send inventory to Amazon’s fulfilment centres, and Amazon handles the rest. Here’s the workflow:

You create a product listing on Amazon and set it live. When customers purchase from you, they receive Prime eligibility and Amazon’s reliable shipping. Amazon picks items from their warehouse, packs them with professional packaging, and ships them to your customers. If something goes wrong, Amazon’s customer service handles complaints and returns. You never touch the product again after sending it to Amazon.

This hands-off approach is FBA’s primary appeal. You focus on sourcing, listing optimisation, and marketing while Amazon manages complex logistics at scale.

FBA Fee Structure

FBA isn’t free. You pay multiple fees that directly impact your profitability. Understanding these is essential before you commit inventory.

FBA Size Tiers and Pricing

Products are categorized into three FBA size tiers, each with different fee rates. Small/Standard tier (items under 2kg) is the most common, with a standard fulfilment fee of approximately £3.58. This covers picking, packing, and shipping to the customer. Larger items fall into the Large Standard tier and cost more. Oversized items incur the highest fees, often £8 or more. Amazon deducts the applicable fee automatically when an order is fulfilled.

Low-Price FBA Rates (2026 Update): Amazon previously offered “Small and Light” FBA rates for products priced under £20 (discontinued in 2023). In 2026, low-price FBA rates have been reintroduced and now apply to any product priced at or below £20, regardless of size category. These products receive a reduced fulfilment fee with an average savings of £0.40 per unit compared to standard rates. If you sell items at or below £20, verify you’re enrolled in this programme to capture these savings automatically.

Fulfilment Fees

Fulfilment fees vary by size tier. For items under 2kg (the standard size tier for most sellers), the fulfilment fee is approximately £3.58. This covers picking, packing, and shipping to the customer. Larger items cost more. Oversized items can cost £8 or more. Amazon deducts this fee automatically when an order is fulfilled.

Monthly Storage Fees

Amazon charges for warehouse space. Standard storage costs £0.87 per cubic foot from January to September, then increases to £2.90 per cubic foot during the peak season (October to December). This fee applies regardless of whether your items sell. If you send 100 units that sit for a month, you pay storage fees for all 100 units.

Storage fees add up quickly for slow-moving items, niche products, or seasonal goods. Plan your inventory carefully to avoid expensive storage costs.

Long-Term Storage Fees

Items stored for 365 days or longer incur additional charges of £6.90 per cubic foot. Amazon introduces this to encourage sellers to keep inventory moving. Slow-moving inventory becomes expensive fast under this model.

Optional Services

Amazon offers add-on services for additional fees. Labelling services cost £0.50 per item if you don’t pre-label items yourself. Returns management handles customer returns for an additional fee. Disposal services remove unsaleable inventory. Most sellers skip these optional services to minimise costs.

Fuel Surcharge

From April 2026, a 3.5% fuel surcharge applies to all fulfilment fees. This reflects transportation costs and will increase your per-unit FBA cost.

2026 FBA Changes: What’s New

Amazon made significant changes to FBA starting in 2026. Awareness of these changes is critical for your planning.

FBA prep services were discontinued in January 2026. Previously, sellers could send unprepped inventory to Amazon, and Amazon would handle labelling and packaging. Now, all inventory must arrive properly prepared. This shifts preparation responsibility and cost to you.

Commingling ended in March 2026. Previously, Amazon mixed identical products from multiple sellers in the same warehouse bin. Now, each seller’s inventory is tracked separately. This prevents commingling loss but means you need robust inventory management systems.

Reimbursements now calculate at manufacturing cost rather than the full sale price. If a unit is lost or damaged, you’re reimbursed at cost, not at your selling price. This change significantly impacts your risk if Amazon damages your inventory.

FBA Fee Updates for 2026

Amazon reduced FBA fulfilment fees across the board, saving UK sellers an average of £0.26 per unit. However, storage fees saw a modest increase of £0.02 per unit. The net result is a favourable reduction of approximately £0.15 per unit on average for most sellers. This fee reduction applies to both standard and oversized categories.

Storage fees during peak season (October-December) increased slightly, so plan ahead: move excess inventory before October to avoid peak storage charges, or ensure that peak-season inventory has high sell-through velocity to minimise storage duration.

FBA vs Self-Fulfillment: Cost Comparison

The decision between FBA and self-fulfillment depends on your specific products. For items under 2kg, FBA at £3.58 is often cheaper than self-shipping, which typically costs £4 or more when you include packaging, courier fees, and your time.

However, this changes for multi-item orders. If customers typically order multiple units, FBA costs compound with each item. Self-fulfillment offers flat-rate shipping that’s cheaper per item. For oversized items, FBA’s size-tier premiums make self-fulfillment more economical.

Calculate your specific costs before committing. Don’t assume FBA is cheaper. Instead, verify with your actual product dimensions, typical order size, and local shipping rates.

Advantages of FBA

FBA offers concrete advantages that justify the costs for many sellers. The Prime badge is valuable. Amazon Prime members often filter out non-Prime offers entirely. FBA automatically qualifies your listings for Prime.

Amazon prioritises FBA sellers for the Buy Box, which is where most sales happen on shared listings. The Buy Box receives 80-90% of sales. Being FBA-eligible significantly improves your odds of winning it.

Customer service is handled by Amazon. Returns, complaints, and damaged items are Amazon’s responsibility. This dramatically reduces your operational burden and customer service workload.

Logistics are entirely hands-off. You don’t manage packing, shipping, or courier relationships. Amazon operates at scale, using their logistics network to ship efficiently.

Disadvantages of FBA

FBA isn’t suitable for every product or seller. Fees directly reduce your profit margins. Items under 2kg might work, but if your margins are under 30-40%, FBA fees consume most of your profit.

Inventory monitoring is complex. You must constantly track stock levels in multiple fulfilment centres across different marketplaces. Running out of stock costs you sales; overstocking costs you in storage fees.

Hazardous materials are prohibited. Electronics, batteries, aerosols, liquids, and anything Amazon classifies as hazardous cannot use FBA. This eliminates entire product categories.

Multi-item orders become expensive. FBA charges per item, so a customer ordering 3 units pays £10.74 in FBA fees (£3.58 x 3). This might be uncompetitive versus competitors using self-fulfillment.

Low-value items don’t work with FBA. If you’re selling items under £5, FBA fees eat most of the profit. FBA is designed for products with healthy margins.

Optional FBA Services

Beyond the core FBA service, Amazon offers enhancements. Labelling services handle pre-shipment labelling if you can’t do it yourself. Returns management streamlines the returns process if you find Amazon’s default handling problematic. Disposal services remove unsaleable inventory at the end of the year.

Most established sellers skip these services and handle labelling themselves or use preparation companies. The costs add up quickly for high-volume sellers.

Pan-EU FBA and Remote FBA

If you sell across multiple European marketplaces, Pan-EU FBA simplifies logistics. Read our Pan-EU FBA guide for details on how this works.

Remote FBA allows you to send inventory to Amazon fulfilment centres from anywhere, not just from your location. Our detailed Pan-EU guide covers both approaches.

When FBA Makes Sense

FBA is right for you if you’re selling items with healthy margins (40%+ gross margin), you have consistent demand that justifies storage costs, you want Prime eligibility, and you prioritise time over marginal cost savings.

FBA works well for branded own-label products where you control pricing and can absorb FBA fees. It’s ideal if you’re scaling to multiple marketplaces and don’t have warehouse capacity.

When FBA Doesn’t Make Sense

Avoid FBA if you’re selling low-margin commodity items, you have seasonal demand with long storage periods, you sell high-volume multi-item bundles, or your products fall into restricted or hazardous categories.

FBA also doesn’t work for extremely niche products with minimal demand. Every month in storage costs money. If you sell one unit per month, storage fees dwarf your profit.

Read our detailed FBA vs FBM comparison for a side-by-side analysis of both fulfillment options.

Getting Started with FBA

Barcode Options: Manufacturer vs Amazon FNSKU

Before sending inventory to FBA, you must select a barcode type. Two options exist: manufacturer barcodes and Amazon FNSKUs.

Manufacturer Barcodes (Commingling): If you use the product’s original manufacturer barcode, Amazon will commingle your inventory with identical products from other sellers in the same warehouse bin. This reduces your individual product tracking but also increases the risk of counterfeit mixing—if another seller sends counterfeit units with the same barcode, those fakes could ship to customers alongside your authentic items, damaging your reputation even though you sent legitimate stock.

Amazon FNSKU (Fulfillment Network Stock Unit): This is a unique barcode Amazon assigns specifically to your inventory. Each seller’s stock is tracked and stored separately, eliminating commingling risk. FNSKU is safer but requires you to label every unit with Amazon’s barcode before sending stock to their fulfilment centre. This increases prep time but provides complete inventory control and eliminates counterfeit-mixing risk.

Labelling Service: If you don’t want to label units yourself, Amazon offers a labelling service where they apply FNSKU barcodes to items after receipt at the fulfilment centre. The cost is approximately £0.50 per label, but this saves substantial time if you’re shipping high volumes.

Inventory Creation Options

You can convert existing FBM inventory to FBA or launch new products directly as FBA. Two methods are available:

Manual Conversion: In Seller Central, select your product, choose “Convert to FBA,” then select your preferred barcode type (manufacturer or FNSKU). Fill in any hazmat information if applicable. This works well for converting one or a few products.

Bulk Inventory Loader: For high-volume conversions, use the Inventory Loader spreadsheet. Download the template from Seller Central, populate it with your ASINs and quantities, specify barcode type and hazmat status, and upload. This method processes dozens of products simultaneously and is much faster than manual conversion.

To use FBA, you need a Professional seller account on Amazon. Create your product listing with complete, optimised information. Then navigate to your inventory in Seller Central and send your inventory to Amazon.