1. Your Inventory Age report
Seller Central → Inventory → Inventory Planning → Inventory age (or Reports → Fulfillment → Inventory Age). Needs sku and the inv-age columns; units-shipped-t30/t90, your-price, item-volume and volume-unit-measurement are used when present. Add a unit cost column if you want per-SKU costs; otherwise the default below is used for every SKU.
2. Your costs and the fee tables (edit these)
These defaults were typed from memory of public fee pages and are not verified against a live account. Amazon changes them; replace them with the current figures from Seller Central before acting.
Choose the report file or paste it, then click Compare options.
Result
By SKU, biggest gain first
| SKU | Units | Aged 181+ | Sold / mo | Margin / unit | Fees if held | Best option | Gain vs hold |
|---|
| Option | Fees in horizon | Profit to sell-through |
|---|
The model, and what it leaves out
- Units by age come from the report's age buckets, dated at each bucket's midpoint. Sales take the oldest units first, at the pace of the units shipped in the last 90 days (or 30, 60 or 7 if that is all there is).
- Fees are charged each 30-day step on the average units held: storage at your per-cubic-foot rate (the Oct–Dec rate is used for those calendar months) plus the aged surcharge for the age each lot has reached.
- Options. Hold; mark down 10, 20 or 30% (less margin per unit, more sales by your elasticity); remove the units at or beyond the aged threshold now (you pay the removal fee, they stop costing storage); remove everything. Each is simulated to sell-through, capped at 36 months, and the best projected profit is named.
- Reconciles. Fees in the horizon are storage plus surcharge, and the by-SKU rows add up to the totals at the top.
- Not modelled: the per-unit minimum on the oldest surcharge tier, inbound placement and low-inventory-level fees, seasonality, restocking (new units reset nothing here), the time value of money, returns, disposal versus liquidation prices, tax, and how a price change affects your ranking or ads. Salvage defaults to zero.
- Unverified: the fee defaults are typed from memory and no real Seller Central export was available when this was written. Column names are matched by alias; if a file is not read the page lists the rows skipped and why.
Common questions
How do I know which FBA inventory to remove or mark down?
Download the Inventory Age report, drop it here, and the tool simulates the next months of storage fees and aged-inventory surcharges for each SKU under four choices: hold, mark down, remove the aged units, or remove everything. It names the one with the best projected profit and how much better it is than holding.
Which report do I need?
Seller Central → Inventory → Inventory Planning → Inventory age (or Reports → Fulfillment → Inventory Age). The columns used are sku, the inv-age buckets, units-shipped-t7/t30/t60/t90, your-price and item-volume. Unit cost is not in the report, so type a default or add a unit cost column.
What is the aged inventory surcharge?
A monthly fee per cubic foot that Amazon has charged on units that have been in a fulfilment centre for a long time, rising with age. The surcharge table on this page is an editable default typed from memory of public fee pages; Amazon changes it, so check the current one in Seller Central before acting.
When does removing units beat holding them?
When the fees the units would keep accruing until they sell, or for as long as the model runs if they never do, are larger than the removal fee plus the profit you would lose on the units you remove. Slow SKUs with old stock and a thin margin are the usual cases; the tool shows the numbers per option.
How is a markdown modelled?
A price cut lowers the margin per unit and raises sales speed by the elasticity you set: with the default of 2, a 10% cut sells 20% faster. That is an assumption, not a measurement of your listing, and a SKU with no recent sales is never lifted by a markdown in the model.
Is my seller data uploaded?
No. The file is read in this browser tab and never leaves your device. There are no accounts, cookies or analytics vendors.