Daily demand
Recent units sold are divided by the selected period. Any seasonal/promotion uplift is then applied.
Free Amazon seller tool
Amazon FBA Replenishment & Stockout Calculator
Estimate when to dispatch your next FBA shipment and how many units to send using your recent sales, current sellable stock, confirmed inbound stock, lead time and safety stock.
Stock coverReorder pointDispatch timingRecommended quantity
Your inputs are calculated in your browser. This tool does not connect to Seller Central or upload your inventory data to CES.
Planning result
Ready to calculate
Your replenishment recommendation
Recommended replenishment—units
Recommended dispatch—based on stock position
Adjusted daily sales—units/day
Current stock cover—sellable stock only
Cover incl. inbound—planning stock position
Total lead time—prep + receiving
Reorder point—lead demand + safety
Projected stock at arrival—before new shipment units
What the result means
Enter your stock, sales and lead-time details, then calculate. The recommendation will explain stockout risk, reorder timing and quantity.
Planning assumption
Confirmed inbound units are treated as stock expected to become available within the planning window. The calculator does not know Amazon capacity limits, FC-level inventory placement, receiving delays, sudden demand changes or stranded/unfulfillable inventory. Confirm operational constraints in Seller Central before dispatch.
How the estimate works
A practical replenishment model
The tool uses recent sales velocity as a baseline, adjusts it for any expected uplift, protects demand through your lead time, and keeps the safety stock you choose.
Reorder point
Adjusted daily demand × total lead time, plus the safety-stock units needed for the safety days you entered.
Quantity to send
The calculator estimates stock remaining when the next shipment arrives, then tops inventory up to your target cover plus safety stock. MOQ and case-pack rounding are applied last.
Practical questions
FBA replenishment calculator FAQs
Which sales period should I use?
Use a period that reflects your current demand. Thirty days is a useful default for a stable product. Use 60 or 90 days when demand is uneven and you want a smoother baseline. For festival or promotion planning, use the uplift field rather than replacing real sales with a guess.
Should I include inbound inventory?
Include only confirmed inbound units you reasonably expect to become available before your sellable stock is exhausted. If an inbound shipment is delayed or uncertain, reduce the inbound quantity so the recommendation stays conservative.
What does safety stock mean here?
Safety stock is extra demand cover kept above normal lead-time demand. It protects against variability such as receiving delays or a temporary sales increase. The right number of safety days depends on your product, supply reliability and risk tolerance.
Why can the recommended quantity be higher than my 30- or 60-day sales?
The recommendation can include demand that will occur before the new shipment arrives, your chosen target cover after arrival, and separate safety stock. MOQ and case-pack rounding can increase the final quantity further.
Does this replace Amazon's own inventory recommendations?
No. This is an independent planning calculator based only on the numbers you enter. Amazon may use additional account, capacity, fulfilment-centre and demand signals that this public tool cannot see.