What Is Distribution Requirements Planning for FBA?
Distribution requirements planning is the process of deciding what inventory to send where, and when, across a multi-node supply chain. In the textbook version, DRP coordinates a central warehouse with regional distribution centers and retail stores. For FBA sellers, the structure is different but the math is the same: you have inventory sitting at multiple locations (3PL, AWD, Amazon's fulfillment network) and you need to decide how to redistribute it as demand evolves.
Most small FBA operations don't formally run distribution requirements planning. They send everything inbound to Amazon and hope for the best. But once your business has a 3PL holding overflow, an AWD account staging inventory, or multiple sales channels (FBA + Walmart + Shopify), DRP becomes essential. Without it, you end up overstocking one channel while another stocks out, and you cannot answer the question "should I move 500 units from my 3PL to FBA this week, or wait?"
Distribution requirements planning is what turns multi-location inventory from a liability into an asset.
The DRP Formula
DRP works as a time-phased table for each stocking location:
Net Requirement (per location, per period) = Forecasted Demand + Safety Stock − On-Hand − In-TransitIf positive, you need a planned shipment to that location. The shipment must originate N days earlier, where N is the transfer lead time from the source node.
Variables:
- Forecasted Demand: Expected sales at this location in the period
- Safety Stock: Buffer specific to that location's variability
- On-Hand: Current inventory at that location
- In-Transit: Units already shipped to this location, not yet received
- Transfer Lead Time: Days from PO at source to receipt at destination
For FBA, the typical "source node" is your 3PL or AWD; the "destination node" is FBA. AWD-to-FBA transfers run 3-7 days. 3PL-to-FBA inbound runs 7-14 days including FBA receiving time.
Worked Example: DRP Across 3PL and FBA
You sell a kitchen gadget at $28.99 ASP. You hold inventory at two locations: your 3PL (1,800 units on hand) and FBA (450 units on hand). FBA demand averages 95 units/week. 3PL-to-FBA transfer lead time: 10 days. FBA safety stock target: 285 units (3 weeks cover).
| Week | FBA Forecast | FBA On-Hand (End) | Net Requirement | Action |
|---|---|---|---|---|
| 1 | 95 | 355 | 0 | None |
| 2 | 95 | 260 | 25 | Transfer needed |
| 3 | 95 | 165 | 120 | Already arriving |
| 4 | 95 | 70 | 215 | Already arriving |
By Week 2, FBA drops to 260 units, below the 285-unit safety target. Net requirement: 25 units. But because you can't ship 25 units economically, and because the lead time is 10 days, the practical DRP decision is: ship 400 units from 3PL to FBA today to cover Weeks 2-4 demand plus rebuild safety stock.
After the transfer: 3PL drops to 1,400 units (still 14 weeks of cover). FBA gets to 850 units arriving in 10 days. The DRP plan keeps both nodes within their target ranges.
FBA-Specific Context for Distribution Requirements Planning
Standard distribution requirements planning assumes you control all stocking nodes. FBA sellers don't control Amazon's network. This creates two unique constraints:
Restock limits as a hard cap: Your DRP might recommend shipping 1,200 units to FBA. Amazon's restock limits may only allow 600. The remaining 600 must stay at your 3PL or in AWD. DRP that ignores this constraint produces plans you can't execute.
FBA receiving as a black box: Once a shipment leaves your 3PL, you don't know exactly when it will be received and counted at FBA. Reserved inventory can sit in transfer status for 3-21 days. Your DRP transfer lead time should be the 90th percentile of receiving time, not the average.
AWD as a buffer node: AWD changes DRP economics significantly. AWD-to-FBA transfers are faster than 3PL-to-FBA (3-7 days vs 7-14 days), but AWD storage is more expensive than a typical 3PL. Smart DRP balances the speed advantage against the cost.
Common Mistakes
1. Treating FBA as the only stocking node. Many sellers send 100% of inventory directly to FBA, then panic when storage limits cap their replenishment. With no buffer at a 3PL, you have nothing to release into FBA when restock limits open up. DRP requires at least two nodes to function.
2. Using a single safety stock target across all locations. Your 3PL doesn't need much safety stock because demand there is just outbound transfers. Your FBA location needs significant safety stock because that's where customer demand happens. Use location-specific safety stock targets.
3. Re-running DRP only when stocking out. DRP is a continuous process. If you only do it reactively, you'll always be behind on transfers. Run DRP weekly even when inventory looks healthy, because it's the planning that prevents the future stockout.
Related Terms
Distribution Requirements Planning FAQ
Do FBA sellers actually need distribution requirements planning?
Yes, if you stock inventory anywhere besides Amazon's fulfillment centers. The moment you have a 3PL, AWD, an MFN warehouse, or a Shopify-fulfilling location, you have multiple stocking nodes and DRP becomes relevant. Sellers running pure single-channel FBA with no buffer storage can ignore it.
How is DRP different from MRP?
MRP plans production and component sourcing upstream of finished goods. DRP plans how to push finished goods downstream to stocking locations. MRP answers "what do I need to make?" while DRP answers "where do I need to send what I have?" FBA sellers using bundles or kitting need both.
Can I use DRP across FBA and AWD?
Yes. AWD acts as your upstream stocking node, FBA fulfillment centers act as the downstream nodes, and DRP determines how much to release from AWD to FBA in each replenishment cycle. This is one of the highest-value DRP use cases for sellers managing restock limit constraints.
How often should I re-run distribution requirements planning?
Weekly at minimum, daily for high-velocity SKUs. DRP outputs go stale fast because demand actuals shift and FBA inbound timelines change. Sellers with significant 3PL holdings should re-run DRP every time they consider an inbound shipment to Amazon.