Free Amazon FBA tool
Amazon Inventory Forecast & Reorder Point Calculator
See when to place your next three purchase orders and the day you'd stock out if you wait. Reorder points, safety stock, and restock timing.
Order next by
On track—
in 26 days — order 504 units
If you don't order
—
stockout in 92 days
—
Today
550 units on hand
—
PO #1
Order 504 units
—
PO #1 lands
630 units on hand
—
PO #2
Order 504 units
—
PO #3
Order 504 units
Units in FBA
Fulfillable stock right now.
Units inbound
Already shipped to FBA.
Avg daily sales
Your last-30-day average.
6/day
Sales trend
Month-over-month change in demand.
0%/mo
Inventory projection
Projected stock
If you don't order
Reorder point
Safety stock
Why —?
550 units on hand ≈ 92 days of cover
45-day lead time + 21-day safety buffer = order while 396 units (≈ 66 days) remain
92 − 66 ≈ 26 days from today — place PO #1 by —
Your next 3 purchase orders
| PO | Place by | Units | Cases | Est. cost | Lands | Stock when it lands |
|---|---|---|---|---|---|---|
| #1 | — | 504 | 21 | $3,276 | — | 126safety floor |
| #2 | — | 504 | 21 | $3,276 | — | 126safety floor |
| #3 | — | 504 | 21 | $3,276 | — | 126safety floor |
Each PO = 60 days of sales (360 units) raised to your 500-unit MOQ, rounded to 21 case packs of 24.
Reorder points, safety stock & restock timing
The stock level at which you must place a new order to avoid running out. It equals the demand you expect during your supplier lead time plus your safety stock: at 6 sales a day, a 45-day lead time, and 21 days of safety stock, that is (45 + 21) × 6 = 396 units. When your fulfillable inventory crosses it, an order placed today lands right as you touch safety stock. Order later than that and you are betting on the carrier.
In Seller Central, open Business Reports, then Detail Page Sales and Traffic. Take the units ordered for the last 30 days and divide by 30. Use the trend slider if that average is clearly rising or falling.
Most FBA sellers carry two to four weeks. Carry more when your supplier's dates wobble, when a single stockout would tank a hard-won ranking, or during Q4, and less for slow, stable products where storage fees outweigh the risk. Set it in days, not units, so the buffer stays honest as sales change: 21 days of safety stock is 126 units at 6 sales a day but 252 at 12. The calculator converts your days to units at your current velocity, so the floor moves with demand.
Every day between placing the PO and the units becoming fulfillable: production, freight, customs, and Amazon check-in. Sellers who only count the factory quote reorder weeks late. Measure your slowest recent order, not your fastest.
The calculator orders the MOQ and spaces your next orders further apart, because a bigger PO lasts longer. Suppliers sell minimums and full cases, not spreadsheet-perfect quantities, so each planned PO covers your chosen days of demand, gets raised to the MOQ if needed, then rounds up to whole case packs. You see it in the cadence: order 504 units at 6 a day and the next PO is not due for 84 days.
The trend you set compounds monthly through every calculation: reorder point, order dates, and quantities. Growing 20% a month means demand over your lead time is higher than last month's sales suggest, so growth pulls orders earlier and makes them bigger. Decline stretches them out, and a steep enough decline shows no reorder needed at all.
Because each order's size sets when the next one is due, a single date hides the pattern. With a long lead time and short coverage you may need to place PO #2 before PO #1 even arrives. One reorder date tells you what to do this week; three dated POs show your reorder rhythm, the cash each one ties up, and your cash calendar for the next two quarters, so you see overlapping orders coming before they collide.