Replenishment Planning: Keeping Stock at the Right Level | Inventory Hero
·5 min readInventory Planning
Replenishment Planning: Keeping Stock at the Right Level
Replenishment planning is the process of restocking to hold target levels without stocking out or overbuying. The inputs, the cadence, and how to run it.
Replenishment planning is the process of deciding when and how much to reorder so your inventory stays at a target level, meeting demand without stocking out or tying up cash in excess. It combines a demand forecast, your supplier lead time, a safety-stock buffer, a reorder point that triggers the order, and an order quantity. Run continuously, it keeps stock flowing in to match stock flowing out.
What is the difference between replenishment and reordering?
Andrew Erickson is the founder of Inventory Hero. He has spent years working with Amazon FBA sellers on demand forecasting, restock planning, and the cash flow side of running a private-label brand. Inventory Hero exists because every spreadsheet-based inventory system he tried eventually broke — usually right before Q4.
Reordering is the individual act of placing an order; replenishment planning is the system that decides when and how much to reorder across your catalog to hold target levels. Reordering answers 'place this order now'; replenishment planning is the ongoing discipline, the forecasts, reorder points, and buffers, that makes each reorder land at the right time and quantity rather than being a reaction.
How do you plan replenishment for Amazon FBA?
Forecast each SKU's demand from its sales velocity, add your full lead time (production, freight, and Amazon receiving), set a reorder point that triggers an order early enough to arrive before you run out, hold safety stock sized to your demand and lead-time variability, and choose an order quantity that balances bulk savings against holding cost. Then track in-transit stock and recompute as demand moves, because FBA lead times are long and variable.
Read article
Replenishment planning is the ongoing process of restocking so you hold target inventory levels without stocking out or overbuying. The short version: it combines a demand forecast, lead time, safety stock, a reorder point, and an order quantity into a system that keeps stock flowing in to match stock flowing out, and it runs continuously because demand and lead times shift. Below are the inputs, the cadence, and how to run it.
Replenishment planning is how you keep inventory at the level that meets demand without excess. Stock flows out as you sell and flows in as you reorder; replenishment planning governs the inflow so it matches the outflow, holding you at a target level rather than swinging between empty and overstocked.
It is the process behind the individual reorder. Reordering answers "place this order"; replenishment planning is the forecasts, reorder points, and buffers that decide when each order should be placed and how big it should be, so the reorders add up to steady, right-sized stock.
Replenishment planning combines a handful of inputs, each answering part of the when-and-how-much question:
Demand forecast. What each SKU will sell, from its sales velocity, trend, and seasonality. Everything else builds on this.
Lead time. How long from placing an order to sellable stock, including production, freight, and Amazon receiving. Long, variable FBA lead times make this critical.
Safety stock. The buffer that absorbs demand spikes and lead-time slips, sized from your variability. See safety stock.
Reorder point. The stock level that triggers an order, set so the new stock arrives before you run out. See reorder point.
Order quantity. How much to order each time, balancing bulk savings against holding cost, often via EOQ.
The reorder point decides when; safety stock and order quantity decide how much. Together they define your replenishment.
A note on the demand input, since it drives the rest: pull each SKU's rolling velocity from Business Reports by ASIN in Seller Central, and use in-stock days only as the denominator. If a past stockout is included, velocity reads artificially low and your reorder point comes out too lean. A velocity built on in-stock days is the correct input for every calculation downstream.
The inputs form a chain that turns a forecast into a specific order:
Forecast demand to get an expected daily sales rate.
Apply lead time to find how much you will sell while waiting for a reorder to arrive.
Add safety stock for the variability in that demand and lead time.
Set the reorder point at lead-time demand plus safety stock, so it triggers an order in time.
Choose the order quantity to bring stock back to a sensible level without overbuying.
Worked simply: a SKU selling 10 a day with a 30-day lead time will sell about 300 units while waiting; add, say, 100 units of safety stock and your reorder point is 400. When on-hand hits 400, you order enough to cover the next cycle. That is replenishment planning in one SKU.
Replenishment planning is not a one-time setup; it is a loop, because the inputs move:
Recompute as demand shifts. A SKU running hot needs its reorder point and quantities revisited, or it stocks out despite a "correct" plan set weeks ago.
Track in-transit stock. Count what is already on order so you neither double-order nor forget committed inventory. This is core multi-location tracking.
Watch lead-time reality. If your supplier or freight slips, your lead-time input, and therefore your reorder points, must move with it.
Review the whole catalog on a cadence, weekly for fast movers, less often for the tail.
The plan is only as good as how current you keep it, which is why replenishment is an ongoing discipline, not a spreadsheet you build once.
The plan usually fails not in its math but in a handful of recurring errors:
Using transit time as lead time. Forgetting production time and Amazon receiving means your reorder point is set on a lead time that is weeks too short, so orders arrive late.
Ignoring in-transit stock. Reordering off your FBA number alone, while a shipment is already on the water, double-orders and creates excess.
A static plan. Setting reorder points once and never revisiting them, so a SKU that sped up or slowed down is planned on stale numbers until it stocks out or piles up.
One rule for every SKU. Treating your erratic long-lead item like your steady fast mover, when they need different buffers and cadences.
Reacting instead of planning. Reordering only when something looks low, which is how a near-stockout becomes a panic order that feeds the bullwhip effect back to your supplier.
Each of these turns a sound framework into late or lumpy orders. Avoiding them is mostly discipline: use your full lead time, count everything you own, and keep the inputs current.
Replenishment planning is the continuous process of restocking to hold target levels, combining a demand forecast, lead time, safety stock, a reorder point, and an order quantity so each reorder lands at the right time and size. The reorder point decides when; safety stock and order quantity decide how much; and keeping the inputs current is what makes it work as demand and lead times move. It is the general discipline behind the FBA-specific restock planning system; for the buffer and trigger math, see safety stock and reorder points.