What a wasted pick-walk actually costs you

Manual order picking is a labour-intensive job, but how much of that labour is actually picking? Most studies put it below a third. The rest — the majority — is travel: walking to the location, walking to the next one, walking back to dispatch. Nobody designed the layout to waste that time, but it happens anyway, and in most operations it stays invisible because nobody has ever turned the steps into a number.

That is the walking bill. It is the labour cost your layout forces that a better layout would not.

Walking is the hidden line item

Most warehouse managers know their pick rate — picks per hour, lines per shift — and they know their labour cost. What they rarely know is how much of that cost is structural: baked into the layout, not the people.

A picker working a mid-sized distribution centre might cover six to ten kilometres in a shift. Most of that travel is sequential: one location to the next, then the next, then back. The route depends almost entirely on where the stock lives — and that was decided, often years ago, when the mix looked different. Fast movers end up at the far end. Slow movers hog the golden ground near dispatch. Nobody moved them because it was never urgent.

The result is a hidden line item in your labour budget. It does not show up on a P&L. It shows up as a slightly higher pick rate than you would need, a slightly higher headcount, a slightly longer shift. It is not inefficiency in the usual sense — your pickers are working hard. It is inefficiency in the layout.

Putting a number on a step

The walking bill calculation is straightforward in principle: travel distance multiplied by picks, multiplied by the loaded labour rate, gives you a cost per year. In practice, getting the right travel distance is the hard part.

Start with a single picker’s day. Take a representative set of orders and trace the route from dispatch, through the picks in pick-sequence order, and back. Measure that route — not as the crow flies, but along legal aisle paths. Multiply by picks per day and days per year.

Use a loaded labour rate, not a basic hourly wage. The cost of a picker in the building is not just their wage — it is wage plus on-costs, employer contributions, shift premium where applicable. A loaded rate for UK warehouse operations is typically somewhere in the high teens to low-to-mid twenties per hour; use your own figure.

Even rough numbers are useful. If your pickers walk an average of 400 metres per van run and you dispatch 120 vans a day, that is 48 kilometres of picking travel per day. At ten minutes of walk time per kilometre, that is 80 hours of walking. Multiply by your loaded rate and by the number of operating days in the year, and you have an annual figure. Even at modest labour rates and modest throughput, the result tends to be six figures. That is the walking bill.

That figure will be wrong. Your routes will vary, your rate will be different, your layout will have quirks. But it will be in the right order of magnitude, and it will be a number you can interrogate.

Why averages hide the problem

Aggregate figures — average distance per pick, average picks per hour — flatten out the variation that tells you where the real problem is. A warehouse average of 3 metres per pick might look acceptable. But look at it by ABC band and you might find A-class picks averaging 2 metres while B-class picks average 8. That is the layout telling you something specific: your B-class stock is too far from dispatch.

The same average hides variation by aisle. A heat map of pick frequency against location often reveals a long tail: a small number of aisles generating the majority of travel, because they are busy but distant. Fixing two or three aisles can shift the average materially.

Pickers also adapt. Experienced pickers learn informal shortcuts — cutting through adjacent aisles, batching nearby picks, adjusting pick sequence on the fly. Their productivity looks fine. But they are compensating for a layout problem, and a new picker or a temporary worker will not have learned the workarounds yet.

What to measure first

Before you change anything, measure the as-is. That means three things: a layout you can work with (a drawing, even a rough one), a pick history (a week or a month of pick records with location codes), and a route estimate.

You do not need a WMS integration or a specialist tool to start. A spreadsheet and a layout drawing will get you to first-order numbers. Mark the pick locations, draw the typical route, and count the steps.

Where it gets harder is testing what-if scenarios: what if you moved the top 50 SKUs to the front three aisles? What would the saving be, in pounds? That calculation requires routing every pick through the changed layout, which is tedious by hand but tractable with a model.

WalkBill does exactly that: sketch your layout, add a pick history, and it runs a month of picking through the model — giving you a £/yr figure for the current state and a comparison against a re-slotted version. It is not a guarantee, but it is a number you can take to a conversation about whether the layout is worth revisiting.

Knowing the walking bill is the first step. Most sites have never calculated it. Calculate yours.