Amazon FBA is convenient. Amazon FBA is also expensive in ways that surprise most sellers when they look closely. The fees that get listed in your Seller Central dashboard are not all the fees you actually pay, and the ones you do see are often joined to your orders in ways that make per-SKU profit hard to calculate.

This guide breaks down every FBA fee category, where it lives in your data, and how to track them properly.

TL;DR: FBA fees fall into five buckets: fulfillment fees per unit, monthly storage fees, long-term storage surcharges, optional service fees (removal, disposal, prep), and referral fees Amazon takes off every sale. Each lives in a different SP-API endpoint or settlement line. Tracking them per SKU per period requires joining at least three data sources, which is exactly what makes FBA fee analytics hard to do in a spreadsheet.

The five fee categories every FBA seller pays

Fulfillment fees

Charged per unit shipped. Amazon calculates them based on size tier and weight. The fee schedule changes during peak season (typically October to January) and resets afterward. Available in your Inventory and Order detail reports through SP-API.

Monthly storage fees

Charged on cubic feet of storage your inventory occupies in FBA warehouses. Standard rates differ for standard-size and oversize products, and increase during peak season. Pulled from the Inventory Storage Fee report.

Long-term storage surcharges

Triggered on inventory aged beyond a threshold (currently 365 days, with previous tiers at 271 and 180 days depending on the period). Heavy penalty for slow-moving stock. Tracked in the Long-Term Storage Fee report.

Optional service fees

Removal orders, disposal, FBA Prep Service, returns processing, unplanned services. Charged per unit. Often discovered in settlement reports rather than your daily ops view.

Referral fees

Amazon’s commission on every sale, typically eight to fifteen percent depending on category. Charged on the gross sale price, not net. Pulled from settlement reports per order line.

Where each fee lives in SP-API

• Fulfillment fees — Order detail reports, settlement line items.
• Storage fees — Inventory Storage Fee report (monthly).
• Long-term surcharges — Long-Term Storage Fee report.
• Optional services — Settlement reports, often as adjustments.
• Referral fees — Settlement reports, attached to each order line.

None of these is in one place. Reporting true cost per SKU means joining all of them by SKU, marketplace and time window.

What sellers commonly miss

• Peak-season fee changes. Fulfillment fees go up in Q4. If your margin model uses average rates, your December margins look better than they really are.
• Removal and disposal fees. Often invisible in dashboards but show up in settlements as adjustments.
• Unplanned services. Mislabeled boxes, missing barcodes, expired stock — all charged but rarely traced back to a product line.
• Inbound shipping costs. Not technically an Amazon fee but part of true unit cost — needs to come from your own data.

How to track FBA fees properly

Useful FBA fee tracking has four properties:

• Per-SKU resolution. Aggregate numbers hide the SKUs that are actually unprofitable.
• Per-marketplace breakdown. Fees vary by region, especially storage rates.
• Time-window comparisons. Same period last year, this period last month, peak vs off-peak.
• Joined to revenue. Fees alone tell you costs. Joined to revenue, they tell you profit.

None of this is mathematically hard. The data engineering is what makes it hard.

The bottom line

FBA fees are not a single number. They are five overlapping fee categories billed through different data flows, on different cadences, with category-specific rules. Real margin per SKU means joining all of them.

DataDoe’s Amazon data layer joins fulfillment, storage, long-term, optional service and referral fees against your sales and ads data per SKU per marketplace — ready for AI tools to query.