Fulfilment: In-House or Outsourced?

Few decisions in e-commerce are as underestimated as the fulfilment question – until the first Christmas season, when the in-house warehouse collapses or the provider ships the wrong parcels. In-house warehouse or 3PL (third-party logistics) isn’t a cost question alone: it’s the decision of whether logistics is your product or your supply chain.

Key takeaways

• The honest cost calculation is full cost per shipment over a whole year – including peak season, not just the quiet month of May.
• In-house operations almost always miss rent, technology, peak staffing and the founder time that goes into the warehouse instead of the business, in most calculations.
• With a provider, returns fees, peak surcharges and the cost of depending on their capacity planning are often missing too.
• Outsourcing wins on speed and focus, doing it yourself wins on brand experience, special logistics or sufficient volume.
• Stock, orders and returns always belong in your own systems (WMS/ERP) – regardless of who does the packing.

The calculation that’s usually set up wrong

The classic mistake: comparing the 3PL price list to the in-house warehouse’s staff costs – and missing half the real cost on both sides.

In-house, calculations almost always miss: rent and service charges per usable square metre, shelving and equipment, sick leave and peak staffing, packaging purchases, stock-count discrepancies – and the most expensive line item of all: the founder time that goes into the warehouse instead of the business. With a provider, what’s missing is: returns and special-case fees, peak surcharges, the cost of error rates you can no longer fix yourself, and dependence on their capacity planning. The comparison only gets honest as full cost per shipment over a whole year – including peak season, not just the quiet month of May.

Worked example: full cost per shipment

Take a product with 2,000 shipments a month. In-house, the naive calculation might only look at the packer’s hourly wage – say, two euros in staff cost per shipment. Add rent, equipment, sick-leave cover, packaging material and a share of management time, and many operations land more in the range of four to five euros full cost per shipment, sometimes more in peak season with temp staff.

A 3PL quote at three euros per shipment looks cheap next to that – until the extra fees for returns, special packaging and peak surcharges are added, which are often only noted in small print on the price list. In the end, both paths often end up closer together than the first glance at the price list suggests. The exact figures depend heavily on product size, volume and category – but the principle of hidden line items on both sides holds across industries.

The real value of this exercise isn’t the one exact number, but calculating both offers by the same system. Anyone who only counts hourly wage for in-house but every extra fee for the 3PL is comparing two different realities. A simple table with identical cost categories on both sides – staff/pick&pack, space/storage fee, packaging, error costs, peak surcharge – makes the comparison solid within a few hours.

What speaks for which path

Outsourcing wins when speed and focus matter: the 3PL brings processes, staffing elasticity and shipping terms that a young store never builds alone – and turns logistics costs from fixed to variable. The price: less control over quality and unboxing, distance from your own product, and switching costs that grow every month.

Doing it yourself wins when logistics is part of the brand promise (packaging experience, same-day, special cases), when the product needs special logistics – or when volume is large enough that the 3PL’s margin could be your own. It’s no coincidence that many large sellers bring fulfilment back in-house exactly when automation like AutoStore makes in-house operations scalable.

Special logistics is its own point that’s often underestimated: refrigerated goods, hazardous materials, very fragile or extremely high-value products don’t find a suitable offer at every 3PL – anyone outsourcing here either pays surcharges for special storage or accepts compromises in handling. In these cases the calculation more often tips towards in-house operations, even at smaller volume, because the error cost of mishandling quickly exceeds the logistics cost.

What to look for in a 3PL provider

A 3PL contract often decides more about the actual cost than the base fee on the first page of the quote.

• Returns process in detail: clarify processing time, quality checks and fee structure before signing, see our article on returns management.
• Make peak surcharges transparent: ask for November/December prices separately, not just the annual average.
• Check system integration: a clean API or EDI connection to your WMS/ERP, no manual spreadsheet reconciliation.
• Get references from a similar category: a 3PL with fashion experience isn’t automatically good for food or electronics.
• Negotiate an exit clause: clarify notice periods and data-return terms in advance, not only when you leave.

The most common mistakes when switching fulfilment

Most problems don’t come from the basic decision, but from how it’s implemented.

• Scheduling the switch just before peak season – fix: put the changeover in the quieter off-season.
• Comparing only the base fee – fix: calculate full cost including all surcharges over a full year.
• Giving up your own systems in the switch – fix: keep running stock and orders in your own WMS/ERP, the 3PL is only the executing hand.
• Switching over completely without a transition phase – fix: plan dual operation for a test phase before switching off the old path.
• Only clarifying the returns process after launch – fix: set the rules contractually before the first parcel ships.

The decision matrix by growth phase

The right solution changes with growth – what’s right in the start-up phase can become wrong at scale.

Phase	Recommendation	Reasoning
Start (up to a few dozen parcels/day)	Pack it yourself	Get to know the product, return reasons and customers directly
Growth	Outsource once logistics becomes the bottleneck	Time gained belongs in product and marketing
Scale	Recalculate: in-house + automation, or hybrid	Beyond substantial sustained volume, control becomes cheaper again

At every phase, the system rule applies: stock, orders and returns belong in your systems, whoever does the packing – otherwise, at the next step, you’re not just switching provider, you’re losing your memory.

From experience: many sellers underestimate how often phases overlap – a core range can already be in the scale phase while a new product line is only just in the start phase. The matrix therefore applies per part of the range, not necessarily to the whole business at once. A hybrid model in practice is often not the exception, but the normal case for sellers who’ve grown.

When a second location or provider pays off

Beyond a certain size, the question is no longer just in-house or 3PL, but whether a second location or a second provider makes sense.

A second location shortens delivery times in more distant sales regions and reduces the risk of a complete standstill if one fails – but costs double the fixed costs and double the process complexity. This usually only makes sense once a single location hits capacity limits, or delivery time to an important region is noticeably behind the competition. Until then, a single, cleanly run location is almost always the better choice over two half-utilised ones.

The bottom line

Fulfilment isn’t a one-off decision, but one that should be recalculated with every growth phase – based on real full cost per shipment, not the first number on a quote. Anyone who keeps their own systems as the backbone can switch between in-house and 3PL without starting from zero. The next sensible step is rarely a decision of principle – it’s usually an honest calculation of the actual cost of the current path.