3PL and 4PL are terms that appear regularly in logistics discussions, but their practical difference is often unclear. For growing eCommerce businesses deciding how to structure their supply chain, understanding which model fits your needs matters.
A third-party logistics provider (3PL) outsources specific logistics functions — typically warehousing, pick and pack, and shipping — on behalf of a business. The business retains control of its inventory, carrier relationships, and operational decisions, but outsources the physical execution to the 3PL. Most UK eCommerce fulfilment centres operate as 3PLs.
A 3PL typically provides: warehouse storage, goods-in receiving, order picking and packing, carrier dispatch, returns handling, and a WMS for real-time inventory visibility. The client manages their own sales channels, product sourcing, and customer relationships.
A fourth-party logistics provider (4PL) sits above the 3PL layer, managing multiple logistics providers on behalf of the client. Rather than operating a warehouse themselves, a 4PL acts as a supply chain integrator — managing the relationships, contracts, and performance of multiple 3PLs, freight forwarders, and customs brokers as a single point of contact.
4PL arrangements are most common in large enterprise businesses with complex, multi-country supply chains where managing multiple providers directly would require a dedicated in-house logistics team. For most SME eCommerce businesses, a 4PL adds cost and complexity without meaningful benefit.
The vast majority of UK eCommerce businesses — from start-up to £50m+ revenue — are best served by a 3PL. You want a single warehouse partner that handles your storage and fulfilment, connected directly to your sales platforms, with transparent per-unit pricing and a direct operational relationship.
A 4PL makes sense when you have 5+ fulfilment locations globally, multiple freight modes (air, sea, road), and supply chain complexity that genuinely requires an orchestration layer above the operational providers.
Speed, simplicity, and cost are the primary drivers. A 3PL like PackPro integrates with your sales channels, dispatches orders the same day, and provides real-time stock visibility through a WMS dashboard — without the overhead of a 4PL management layer. Learn more about PackPro's 3PL services or view our pricing.