Free Amazon inventory calculator
Calculate inventory runway and a simple reorder point from your own inputs.
Enter average daily units, supplier lead time, safety-stock days and current inventory. Add inbound stock if relevant. CEILR shows days of cover, the lead-time + safety-stock threshold and any simple unit gap.
Transparent inventory math
Use the threshold as a planning signal, not a demand forecast.
The calculator does not predict Amazon sales. It applies your selected run rate to your stock, lead-time and safety-stock assumptions.
Show the working
Current days of cover = current sellable units ÷ average daily units.
Simple reorder point = average daily units × (supplier lead-time days + safety-stock days).
Projected available units = current sellable units + inbound units.
Simple replenishment gap = max(0, reorder point − projected available units).
This is intentionally simple. It does not model seasonality, future growth, Amazon receiving delays, supplier variability, minimum order quantities, purchase-order timing or cash capacity.
What a real reorder decision still needs
Inventory threshold is only one gate.
A commercial reorder also needs supplier terms, landed cost, cash commitments, inbound timing, expected demand changes and the consequences of stockout or overstock. CEILR's authenticated inventory/cash workflows are designed to connect those layers.
Educational planning aid only. It does not guarantee supplier delivery, Amazon receiving time, future sales, stockout prevention or profitability. See CEILR methodology.
Connect stock to cash