How a size-tier error overcharges every FBA unit
Amazon's FBA fulfilment fees are driven by a product's size tier — and that tier is calculated from its recorded dimensions and weight. When those measurements are wrong, the overcharge repeats on every unit.
Fees follow the size tier
Amazon groups FBA products into size tiers based on each unit's dimensions and weight. Every tier carries its own per-unit fulfilment fee, and storage is charged by the volume a product occupies. Which tier a product lands in depends on thresholds — limits on length, width, height, and weight. Cross a single threshold, even slightly, and the product moves into the next, more expensive tier.
Why a tiny error becomes a big number
Because the fulfilment fee is charged per unit, a misclassification doesn't cost you once — it costs you on every unit shipped, and an overstated size can raise storage costs too. Multiply a small per-unit difference across thousands of units and months of sales, and a rounding error in one recorded dimension quietly turns into a meaningful sum.
Why it's so easy to miss
Dimensions are often captured once, early in a product's life, and rarely re-checked. FBA fee breakdowns are detailed and change over time, so an overcharge blends into normal variation. Unless you compare a product's recorded measurements against its true size, there is little to flag that anything is wrong.
Signs your product may be mis-tiered
- Fulfilment fees look high relative to the product's true size, or to similar items in your catalogue.
- The product sits close to a tier boundary on one dimension or on weight.
- Fees changed after a catalogue update, repackaging, or a category change.
- The dimensions Amazon has on record don't match what you measure today.
What you can do
- Check the dimensions Amazon has on record against the product's actual measured size, including its packaging.
- If they're off, request a re-measurement so Amazon corrects the size tier going forward.
- Review the fees charged during the period the error was in place — overcharges from that window may be recoverable.
How EvenFee helps
EvenFee audits your FBA fees and dimension records to find measurement-driven overcharges, helps trigger re-measurements, and helps prepare reimbursement claims — on success-based pricing, so you only pay a success fee on amounts actually recovered.