What Is a 3PL? A Plain-English Guide to Third-Party Logistics
If you sell physical products and you are tired of packing boxes, someone has probably told you to "just use a 3PL." So what is a 3PL, and does it actually make sense for you? A 3PL is a third-party logistics provider: a company you pay to store your inventory, pick and pack orders, and ship them to your customers on your behalf.
Here is what a 3PL really does, what it costs with a worked example, how it compares to doing fulfillment yourself, and the one thing most people forget to plan for.
What is a 3PL, exactly
3PL stands for third-party logistics. Instead of holding stock in your garage, a spare room, or your own warehouse, you send it to the 3PL's facility. When an order comes in, their staff pull the items off the shelf, box them up, slap on a shipping label, and hand them to a carrier.
You still own the inventory. You still own the customer relationship. What you outsource is the physical work of storing and moving product. The 3PL is the warehouse and the packing crew you rent instead of build.
Most 3PLs plug into your store or your systems so orders flow to them automatically. You sell, the order lands in their system, they ship it. You are not emailing spreadsheets around.
What a 3PL actually does
The core services are consistent across providers, even if the pricing names differ:
- Receiving. They accept your inbound shipments, count them, and check for damage before putting them away.
- Storage. Your stock sits in their facility, usually billed by the pallet, shelf, or bin per month.
- Pick and pack. For each order, they pick the right items and pack them, sometimes with your branded boxes or inserts.
- Shipping. They hand off to carriers, often at negotiated rates cheaper than you would get on your own.
- Returns. Many handle reverse logistics too: receiving returns, inspecting them, and restocking or disposing.
Better 3PLs add kitting (bundling items into a single SKU), lot and expiry tracking, and same-day cutoffs. The baseline, though, is receive, store, pick, pack, ship.
3PL vs 4PL vs doing it yourself
These terms get thrown around loosely, so here is the honest version:
| Model | Who runs it | Best for |
|---|---|---|
| Self-fulfillment | You store and ship everything | Early stage, low volume, or highly custom packing |
| 3PL | A provider does the physical fulfillment; you manage inventory and orders | Growing brands that want to stop packing boxes |
| 4PL | A partner manages the entire supply chain, including multiple 3PLs | Larger operations with complex, multi-vendor logistics |
A 4PL is a layer above a 3PL. It coordinates carriers, 3PLs, and suppliers on your behalf and hands you a single point of contact. Most small and mid-sized sellers never need a 4PL. If you are asking "what is a 3PL," you are almost certainly choosing between self-fulfillment and a 3PL.
What a 3PL costs: a worked example
3PL pricing is not one number. It stacks several fees, and the mix is what determines whether it saves you money. Typical line items:
- Receiving: a per-pallet or per-hour fee to take in your stock.
- Storage: per pallet or per bin, per month.
- Pick and pack: a fee for the first item in an order, plus a smaller fee per additional item.
- Postage: the actual carrier cost, usually passed through with a small markup.
Say you run an ecommerce brand shipping 1,000 orders a month, averaging 1.8 items per order, and you hold 20 pallets of stock. A common fee structure looks like this:
Storage: 20 pallets x $15 = $300
Pick + pack: 1,000 x $2.50 (1st item) = $2,500
1,000 x 0.8 x $0.50 = $400
Receiving: (averaged monthly) = $400
-----------------------------------------------
Fulfillment total (excludes postage) = $3,600
That is $3.60 per order before postage. Add real shipping on top. Now compare it against your own cost: warehouse rent, staff wages, packing materials, and your own time. For a lot of brands, once you cross a few hundred orders a month, the 3PL wins on pure dollars, and it wins bigger once you factor in the hours you get back.
The trap is low-volume, high-storage products. If you hold a lot of slow-moving stock, storage fees pile up while pick-and-pack revenue for the 3PL stays low, and some providers add long-term storage surcharges. Run your own numbers with your real order profile before you sign anything.
When a 3PL makes sense
Outsourcing fulfillment pays off when specific signals show up. Watch for these:
- Packing is eating your week. If you or your team spend more time in the packing station than growing the business, that time has a cost.
- You are shipping across regions. A 3PL with multiple facilities cuts transit times and shipping cost by holding stock closer to customers.
- Volume is steady and predictable. 3PLs shine on consistent throughput. Wildly spiky demand can rack up surprise fees.
- You want better carrier rates. 3PLs ship in bulk and pass on rates you cannot negotiate solo.
If none of these are true yet, self-fulfillment is probably still the right call. There is no prize for outsourcing early.
The catch: you lose visibility
Here is the part that bites people. The moment your stock leaves your building, you are trusting someone else's system to tell you what you have. Different 3PLs run different portals, and if you use more than one, or you also hold some stock yourself, your inventory truth is now scattered across systems that do not agree.
You need a single source of truth for stock that sits above any one 3PL. That means an inventory system you control, syncing quantities in from wherever product physically lives, so your reorder decisions and your storefront use the same numbers. A solid REST and GraphQL API and webhooks make that sync straightforward: the 3PL reports a shipment, your system decrements the count, and every channel stays honest.
Multi-location support matters here too. If a 3PL splits your stock across two warehouses, or you keep some inventory in-house, you want to see each location separately and still get one accurate total.
Where Inventoros fits
Inventoros is a free, open-source, self-hosted inventory system that gives you exactly that source of truth. It tracks stock across multiple locations, exposes REST and GraphQL APIs plus webhooks to sync with any 3PL, and you host it yourself, so your inventory data stays yours instead of living inside a vendor's portal. It even ships an MCP server so you can query stock in plain language. Setup guides for cPanel, a VPS, and Docker are in the documentation.
FAQ
What is the difference between a 3PL and a warehouse? A warehouse is just storage space. A 3PL stores your goods and does the work: receiving, picking, packing, shipping, and often returns. You can rent a warehouse and staff it yourself, or pay a 3PL to handle the whole operation as a service.
How much does a 3PL cost? There is no flat rate. Expect stacked fees for receiving, monthly storage, pick and pack (a first-item fee plus a smaller per-additional-item fee), and postage. In the worked example above, fulfillment ran about $3.60 per order before shipping. Your number depends on order volume, items per order, and how much stock you store.
Do I still control my inventory if I use a 3PL? You own the inventory, but the 3PL holds the physical count. That is why you want your own inventory system syncing quantities in over an API, so you are not dependent on a single provider's dashboard for the truth.
When should I switch from self-fulfillment to a 3PL? When packing starts stealing time you need for growth, when you are shipping across regions and want stock closer to customers, and when your volume is steady enough to earn better carrier rates. If you are still shipping a handful of orders a day, keep doing it yourself.