What Is a 3PL? Third-Party Logistics Explained for Online Sellers
What a 3PL does, how third-party logistics works for an Amazon or Walmart seller, how it differs from a 4PL, and whether Amazon FBA counts as one.
What is a 3PL? It is the warehouse partner that stores, packs and ships products for sellers who would rather not do that work themselves. Third-party logistics, also written 3rd party logistics, is how many online sellers grow past the spare room without leasing a warehouse. This guide covers the 3PL definition, the services a 3PL warehouse runs, the 1PL to 5PL ladder, and where Amazon FBA fits.
What does 3PL stand for?
3PL stands for third-party logistics: a company you hire to run the physical side of selling online. A 3PL receives your inventory at its warehouse, stores it, picks and packs each order, ships it to your customer and handles returns, so you can sell without keeping stock at home or hiring warehouse staff.
The “third party” is the outside company sitting between you (the first party, the seller) and your customer or carrier. You will also see it called a third-party logistics provider, a fulfillment partner or a 3PL warehouse. The word covers 3PL logistics services of every size, from a single building that ships parcels for small sellers to national networks that move freight for large brands.
How a 3PL Works for an Online Seller
Once a 3PL holds your stock, the work runs in the same order for every product:
- 1
You send a PO and the stock
Your supplier ships to the 3PL's warehouse instead of to you, and you tell the 3PL what is coming.
- 2
The 3PL receives and stores it
Each delivery is counted against the PO, checked for damage and put on a shelf location.
- 3
Orders route to the warehouse
Your sales channels send each order to the 3PL, which picks the item, packs it and labels it.
- 4
The carrier ships it
Tracking goes back to the order, so your customer and the marketplace see it move.
- 5
Returns come back to the 3PL
Each return is inspected and restocked or disposed of based on its condition.
- 6
Your stock counts stay current
Inventory updates in your software as stock comes in and goes out, so you do not oversell.
What does a 3PL warehouse do?
A 3PL warehouse receives your inventory, checks it against your purchase order, stores it, picks and packs each order, ships it with a carrier and processes returns. Many also prep inventory for Amazon FBA and Walmart WFS, assemble kits and bundles, and sync stock counts to your sales channels so your listings match the shelf.
The services a 3PL warehouse usually offers, with the Ecom Circles page for each:
Deliveries checked in against your PO and stored until they sell.
Each order picked from the shelf, packed, labeled and handed to the carrier.
Labels, poly bags and boxes done to Amazon's rules before stock goes into FBA.
The same prep work, to Walmart Fulfillment Services' rules.
Several items assembled into one sellable kit or bundle.
Stock held at the warehouse and shipped straight to your customer when an order comes in.
Returned orders inspected, then restocked or disposed of.
Stock counts kept in step with your sales channels.
What is the difference between 3PL and 4PL?
A 3PL runs the warehouse work itself: it stores your stock, packs your orders and ships them. A 4PL manages the whole supply chain for you, often hiring and coordinating several 3PLs, carriers and freight forwarders without running a warehouse of its own. Most online sellers need a 3PL; 4PLs serve large brands with complex supply chains.
The full ladder, from doing it all yourself to handing off the whole network:
| Level | What it does | Example |
|---|---|---|
| 1PLFirst-party logistics | You move your own goods with your own people and space. | Packing orders at home and dropping them at the post office. |
| 2PLSecond-party logistics | A carrier that owns trucks, planes or ships and moves goods from one place to another. | A parcel carrier delivering an order to your customer. |
| 3PLThird-party logistics | Outsourced warehousing and fulfillment: receiving, storage, pick and pack, shipping and returns. | A fulfillment warehouse that ships your Amazon FBM and Walmart orders. |
| 4PLFourth-party logistics | Manages the whole supply chain, coordinating several 3PLs and carriers, usually without warehouses of its own. | A lead logistics provider running a large brand's network. |
| 5PLFifth-party logistics | The loosest term: plans and runs logistics networks for many clients at once, often buying capacity in bulk. | A provider pooling many shippers' volume to buy carrier and warehouse space. |
Is Amazon a 3PL?
Not in the usual sense. Fulfillment by Amazon (FBA) stores and ships your products for orders placed on Amazon, so it acts like a 3PL for that one marketplace. A 3PL works for you across every channel: it ships your Walmart, FBM and website orders from one stock pool and preps the shipments you send into FBA.
Many FBA sellers still use a 3PL: to hold the stock waiting to go in, to prep it, and to ship the orders FBA does not cover. Here is how the two compare:
| Fulfillment by Amazon (FBA) | A 3PL | |
|---|---|---|
| Whose orders it ships | Orders placed on Amazon (Multi-Channel Fulfillment can ship other channels' orders from FBA stock, on Amazon's terms) | Orders from every channel you sell on |
| Where your stock sits | Amazon's fulfillment centers, placed by Amazon | The 3PL's warehouse |
| Prep for FBA | Your job: Amazon ended its own FBA prep service on January 1, 2026 | Many 3PLs prep and ship your inbound FBA shipments |
| Rules you follow | Amazon's packaging, labeling and capacity rules | Your agreement with the 3PL |
When an Online Seller Needs a 3PL
Sellers usually move to a 3PL when one of these becomes true:
- Packing orders takes hours you would rather spend sourcing and listing.
- Inventory has outgrown the space you have.
- You sell on more than one channel and want one stock pool to fill every order.
- You send stock into Amazon FBA or Walmart WFS and need it prepped to their rules.
- Returns pile up because nobody has time to inspect them.
A 3PL bills for each piece of that work, so the cost moves with your volume. To compare providers, read their rate tables line by line; ours is on the 3PL pricing page. If you want a provider near your suppliers, the directory of 3PL and prep companies lists them by state and service.
Ecom Circles as Your 3PL
Ecom Circles runs 3PL fulfillment for Amazon and Walmart sellers anywhere in the US from warehouses in the Chicago area and Atlanta. We receive your inventory, prep it for FBA and WFS, ship your FBM and Walmart orders, and handle the returns. POs, inventory check-ins, fulfillment and every charge run through your Ecom Circles software, so stock counts sync to your sales channels automatically.
See Ecom Circles warehouse services3PL FAQ
What does 3PL stand for?
3PL stands for third-party logistics: a company you hire to run the physical side of selling online. A 3PL receives your inventory at its warehouse, stores it, picks and packs each order, ships it to your customer and handles returns, so you can sell without keeping stock at home or hiring warehouse staff.
What is the difference between 3PL and 4PL?
A 3PL runs the warehouse work itself: it stores your stock, packs your orders and ships them. A 4PL manages the whole supply chain for you, often hiring and coordinating several 3PLs, carriers and freight forwarders without running a warehouse of its own. Most online sellers need a 3PL; 4PLs serve large brands with complex supply chains.
Is Amazon a 3PL?
Not in the usual sense. Fulfillment by Amazon (FBA) stores and ships your products for orders placed on Amazon, so it acts like a 3PL for that one marketplace. A 3PL works for you across every channel: it ships your Walmart, FBM and website orders from one stock pool and preps the shipments you send into FBA.
What does a 3PL warehouse do?
A 3PL warehouse receives your inventory, checks it against your purchase order, stores it, picks and packs each order, ships it with a carrier and processes returns. Many also prep inventory for Amazon FBA and Walmart WFS, assemble kits and bundles, and sync stock counts to your sales channels so your listings match the shelf.
How does a 3PL make money?
A 3PL charges for each piece of work it does for you: receiving a delivery, storing your inventory, picking and packing each order, and processing each return. Some also charge a one-time setup fee, and postage is usually billed on top. Ask for the full rate table before you sign, so every line on the invoice is one you expected.
Is a 3PL the same as a fulfillment center?
Close, but not quite. A fulfillment center is the building where orders are packed and shipped. A 3PL is the company you hire, and it may run several fulfillment centers plus the receiving, storage, prep and returns work around them. Amazon's fulfillment centers, for example, run Amazon's own network under Amazon's rules.