- Forecast from recent demand but adjust for seasonality and promotions.
- Reorder point should account for lead time, not just current stock.
- Safety stock protects against variability but excessive stock creates its own cost.
- Track fulfilment-centre availability and stranded or unfulfillable units separately from sellable stock.
Start with realistic sales velocity
Calculate recent average daily sales using a period that reflects the current business. Do not blindly average a period that included a major stock-out, one-time promotion or unusual seasonal spike without adjusting for it.
Add procurement and inbound lead time
Estimate how many days it takes to procure, prepare, ship and receive replenishment into FBA. Reorder planning should begin before current inventory reaches zero because inbound stock is not instantly available for sale.
Use safety stock intentionally
Safety stock provides a buffer for demand variation and inbound delays. The right buffer depends on product stability and lead-time uncertainty. More is not always better because slow-moving inventory can increase storage exposure.
Separate inventory states
When planning replenishment, distinguish sellable FBA stock from inbound, reserved, stranded and unfulfillable units. Merchant-fulfilled inventory should also be considered separately if the goal is to position stock closer to FBA customers.
Days-of-cover and reorder example
Days of cover = available sellable units ÷ average daily units sold. Example: 180 units ÷ 6/day = 30 days cover. A simple reorder point can start with expected demand during replenishment lead time + safety stock, then be adjusted for inbound stock, reserved inventory, stock-out history, promotions and regional demand.
- Use a stable demand window and remove obvious stock-out distortion.
- Treat sellable, reserved and inbound stock separately.
- Model promotional or seasonal lift instead of using ordinary daily sales unchanged.
- For multi-FC or regional planning, calculate demand and cover separately where the data supports it.