Merge FBA Inventory Snapshots Without Inventory Double-Counting
Amazon's FBA Inventory reports (GET_FBA_MYI_UNSUPPRESSED_INVENTORY_DATA) are point-in-time snapshots — each export captures quantity_available, quantity_inbound_working, and quantity_reserved at the exact moment of generation. Sellers who download weekly snapshots to track inventory velocity and forecast replenishment needs accumulate multiple files containing the same SKUs at different time points. Merging these files for trend analysis requires careful deduplication logic. The common failure mode: appending 4 weekly snapshots into one workbook and building a Pivot Table on FNSKU produces Sum of quantity_available that is 4x the actual inventory level. If SKU ABC-001 had 1,200 units available in each of the 4 snapshots, the Pivot shows 4,800 — triggering the replenishment system to under-order by 3,600 units. This workflow merges multiple inventory TSV files and deduplicates by FNSKU, preserving the most recent snapshot for accurate stock-level reporting.
Why this matters?
A home goods seller with 180 FBA SKUs merged 8 weekly inventory snapshots into a single file for their replenishment planning spreadsheet. Their inventory model used AVERAGE(quantity_available) across the merged dataset to calculate reorder quantities — but because each SKU appeared 8 times with varying stock levels, the average included weeks when inventory was already depleted, dragging the average artificially low. The model recommended ordering 2.4x the actual needed quantity. The resulting 127,000 over-order incurred $18,400 in FBA long-term storage fees over the next 90 days, and 14 SKUs hit the Aged Inventory Surcharge threshold (271+ days).
The 3-Step Solution
Follow this streamlined workflow to transform your raw data export into a clean, analysis-ready dataset. Each step leverages our browser-based tools to ensure your sensitive data never leaves your device.
By following these three steps, you eliminate manual data wrangling, reduce human error, and maintain full GDPR compliance throughout the process.
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