Overview

Amazon’s FBA Sales Lift tool, located inside Seller Central, quantifies the change in unit sales when a seller moves a SKU from self‑fulfillment to Fulfillment by Amazon. The feature automatically appears when enough comparable data exist, letting merchants decide whether the extra FBA fees are offset by higher sales volumes.

Key Points

• Automatic activation — The dashboard shows the tool only after Amazon’s system detects at least 28 days of sales for the same SKU under both fulfillment methods; sellers do not need to turn it on manually.
• Side‑by‑side comparison — For each qualifying product, the tool lines up identical calendar windows (e.g., 40 days of self‑fulfillment versus the next 40 days of FBA) and measures the unit‑sale difference.
• Data‑minimum rule — A SKU must have a minimum of 28 days of sales history in both the self‑fulfilled and FBA‑fulfilled states before it is eligible for analysis.
• 12‑month lookback — Amazon scans the previous 12 months of your account activity to locate SKUs that have been stocked and sold through both channels, ensuring a broad enough sample.
• Selective inclusion — Only products with sufficient, comparable sales data appear; the lift percentages you see will therefore represent a subset of your catalog, not the total sales picture.
• Seasonality blind spot — The calculation does not adjust for seasonal spikes or dips, so a lift observed during a holiday surge may overstate the true fulfillment effect.

How the FBA Sales Lift Calculation Works

1. Identify eligible SKUs — Amazon pulls every product that has at least 28 days of sales as self‑fulfilled and another 28‑day block as FBA‑fulfilled within the last year. For example, a kitchen gadget sold 120 units over a 30‑day self‑fulfillment window and later sold 156 units over the next 30‑day FBA window.
2. Match time periods — The system aligns the two windows so they cover the same number of days and comparable calendar dates when possible, eliminating differences caused by varying lengths of observation. In the kitchen gadget case, both windows span exactly 30 days, providing an apples‑to‑apples basis.