It’s 2pm on a Wednesday. One of your engineers is halfway through a job, they’ve found the problem, and the part they need isn’t in the van. They call the office. You tell them to head to the nearest merchant, pick it up, and finish the job rather than booking a return visit. An hour later they’re back on site, the job gets done, the customer is happy enough, and the day moves on.
That hour just cost you around £35 in labour, probably £10 in fuel, and a job that was scheduled for 2pm is now running into the next slot. Nobody logs any of that. The invoice goes out for the same amount it would have anyway. From the outside, everything looks fine.
This is the van stock problem most field service businesses actually have. Not the obvious callback that gets tracked and complained about. The quiet, invisible costs that compound daily and never make it onto any report.
Van stock isn’t just about callbacks
The return visit is the most visible cost of poor van stock, but let’s not dismiss it quickly either. According to the Aquant 2024 Field Service Benchmark Report, which analysed over 24 million work orders across 145 service organisations, the industry average first-time fix rate sits at 76%. That means roughly one in four jobs requires a second visit. Bottom-performing organisations fix the issue on the first visit only 55% of the time.
If you want to understand the full cost of that in your own business, the calculation is straightforward. Take an engineer whose total employment cost runs to around £40,000 a year: salary, employer National Insurance, pension contributions, and holiday cover. Divide that by around 200 working days and you’re at roughly £200 per day, or £25 per hour fully loaded. A return visit that takes two hours plus 45 minutes of travel costs you around £85 before you’ve accounted for fuel. Run that across ten engineers doing one unnecessary return visit a week each and you’re spending over £40,000 a year on callbacks alone. If you want a tighter picture of those job-level numbers, the job costing article covers the maths in more detail.
But here’s the thing: the return visit is easy to count. You know it happened. What’s harder to count is everything else.
Fieldmotion Brochure
See how Fieldmotion helps field service teams manage jobs, schedule staff, create invoices, and communicate with customers — all from one easy-to-use system.
The engineer at the merchant: what a parts run actually costs
An engineer is midway through a job. They’ve diagnosed the problem. The part they need isn’t on the van. Rather than booking a return visit, they drive to the nearest merchant or trade counter, pick up what they need, and come back to finish the job in the same visit.
From a customer satisfaction perspective, this looks fine. From a business perspective, it’s expensive and invisible.
A 20-minute drive each way to a trade counter is 40 minutes of non-billable time. Add 15 minutes browsing, waiting, or hunting down the right part and you’re at close to an hour. On a day with four jobs scheduled, that hour doesn’t compress. It pushes the last job back, or the engineer drops it, or they end up running overtime. None of that time gets logged as lost. It just disappears into the gap between what the job was quoted for and what it actually took.
Research by the Aberdeen Group found that field service technicians spend an average of only 3.3 hours per day on actual billable work, with the rest absorbed by travel, admin, and exactly this kind of unplanned downtime. A business that gets that number to 4.5 hours per engineer per day, through better scheduling, less admin, and parts being on the van when they’re needed, has effectively added a quarter of an engineer’s productive capacity without hiring anyone.
There’s also a parts pricing problem buried in the merchant run. Engineers picking up parts ad hoc from a trade counter are paying retail or trade counter prices. The same part ordered through your regular supplier account, in the right volume, on a purchase order, at your negotiated rate, costs less. It also creates a paper trail. The merchant run creates neither.
The overstocking problem nobody talks about
Poor van stock management has two failure modes. The one that gets attention is understocking: the engineer doesn’t have the part, the job can’t be completed, everyone is inconvenienced.
The one that gets far less attention is overstocking, and it carries its own costs.
An engineer who’s been caught out without a part enough times tends to compensate. They start carrying more. When one part turns out to be useful once, it goes on their unofficial mental list of things to always carry. When something fails unexpectedly on a job and they happened to have a spare, that spare becomes permanent inventory. Over time, the van accumulates.
The costs of that accumulation add up quickly. Overloaded vans use more fuel, parts that sit for six months without being used are often parts that could have been returned or transferred to another engineer who actually needed them, and some parts (particularly filters, seals, and certain electrical components) degrade over time and become unusable before they’re ever fitted. An engineer spending two minutes searching through disorganised bins for a part they know is somewhere is burning time on every single job.
One service contractor profiled by eTurns reduced the average line items on each van from 315 to 170 and cut inventory value per van from $20,000 to $14,000 after implementing a proper tracking system. Their total carrying costs fell by more than $700,000 annually. That’s an extreme example from a large operation, but the principle scales down directly.
For a 10-engineer business carrying £5,000 of stock per van, a 30% reduction in excess stock through better tracking frees up £15,000 in tied-up capital, money that’s currently sitting in the back of ten vans doing nothing.
Why engineers hoard parts (and why it’s not their fault)
It’s worth spending a moment on the human side of this problem, because the instinct is to see a van full of parts that aren’t needed and blame the engineer. That’s the wrong lens.
Engineers carry too much because the system hasn’t given them a reason to trust it. If parts are restocked reliably, if they can check what’s on the van before they leave and know the information is accurate, if they know that ordering a part for a job actually results in that part being there when they need it, then they don’t need to hoard. The hoarding is a rational response to an unreliable process.
One HVAC business owner quoted by ServiceTitan described this dynamic directly: “I have three technicians who are 62 years old. They say, ‘I like my truck this way’ or ‘I like having all these parts.’ They do provide their own inventory lists to our warehouse person to restock before they go out every morning, but we do not have our own formal system for that.”
Those engineers aren’t being obstructive. They’ve built their own system because the business hasn’t provided a better one. The fix isn’t a conversation about carrying too much stock. It’s building a process they can trust more than their own informal list.
That matters because when you move engineers from self-managed to system-managed van stock, you get three things back: accurate stock records, reduced overstocking, and the psychological shift from “what do I think I’ll need” to “what does the job actually require.” The last one is the most valuable.
The unlogged parts problem
This one deserves its own section because it’s often the largest financial leak, and almost no one tracks it.
An engineer is on a job. They fit a part. They don’t log it, not from laziness, but because they’re focused on finishing the job, the customer is waiting, and logging parts feels like admin that can wait or that the office will sort out. The job gets signed off. The invoice goes out for labour. The part doesn’t appear on the invoice because it was never logged against the job.
That part came off the van. It costs the business money. It isn’t charged to the customer. And because it wasn’t logged, the stock count for that van is now wrong, which means the next engineer who needs that part may not find it, which leads to either a merchant run or a return visit.
This is a compounding problem. Unlogged parts create inaccurate stock counts, inaccurate stock counts create unexpected shortages, unexpected shortages create either merchant runs or callbacks, and the whole cycle repeats. Meanwhile, the job margin on every job where parts aren’t logged is artificially inflated. It looks better than it is because a portion of the cost has simply disappeared.
Research consistently shows that field service businesses lose between 5% and 15% of parts value to this kind of shrinkage and billing leakage. For a business spending £100,000 a year on parts, that’s between £5,000 and £15,000 of cost that’s either not being charged to customers or not being tracked at all.
The answer is a process that makes logging parts as easy as possible: preferably at the point of use on a mobile device, linked directly to the job and the invoice so that what comes off the van appears on the bill without anyone having to remember to add it separately.
What good van stock management looks like in practice
There’s no universal answer to what should be on a field service van, because the right answer depends entirely on what jobs that van is being sent to. But the principles of managing it well are consistent regardless of trade or business size.
The starting point is a standard stock list set by the business, not by individual engineers. Every van should carry a defined core of the parts most commonly needed for the jobs it runs, reviewed quarterly as the job mix changes. Leaving each engineer to decide what’s standard is how you end up with ten vans carrying ten different inventories, none of which anyone outside that engineer can reliably predict or restock.
On top of the core list, jobs where specific parts are known in advance should have those parts confirmed before the engineer leaves. A pre-departure check doesn’t need to be elaborate. A digital checklist linked to the day’s jobs takes a few minutes and catches the gaps before they become a mid-job merchant run or a callback.
The mechanics of keeping core stock at the right level work best as a minimum/maximum system. Each part on the standard list has a floor quantity that triggers a reorder and a ceiling that stops restocking short of excess. When stock drops below the minimum, a purchase order or transfer request is raised. When the restock arrives, it fills to the maximum and stops. Restaurant kitchens run their walk-in coolers this way because it eliminates the two failure modes at once: running out and over-ordering. It works just as well for filters, fittings, and consumables.
The discipline that holds all of this together is logging parts at the point of use. The mobile device an engineer already carries for job sheets and customer signatures should be where parts get recorded, linked to the specific job, feeding through to the invoice automatically. Weekly quick counts of high-turnover items take less than 15 minutes and catch drift before it compounds. A quarterly review of what’s moving and what isn’t adjusts the stock list to reality rather than assumption.
None of this is complicated. The businesses that do it well aren’t doing something sophisticated. They’ve just replaced the informal, engineer-by-engineer system with one the whole team works from.
The job history connection
The difference between businesses that manage van stock well and those that don’t often comes down to whether they use their job data to make stocking decisions, or whether they’re still making stocking decisions from memory.
If an engineer has visited a particular customer’s site six times in two years and used the same three parts on four of those visits, those parts should be on the van every time that site appears in the schedule. A boiler model that generates the same fault most times it needs attention should have those parts as standard stock for any engineer covering that equipment. A job type that accounts for 40% of your work volume and consistently requires the same consumables should have minimum quantities set to reflect that reality, not whatever felt reasonable when someone first built the system.
That kind of intelligence doesn’t require anything elaborate. It requires job records detailed enough to show which parts were used on which jobs, and a process that reviews that data when setting stock levels rather than relying on an engineer’s recollection or a list that was built two years ago and hasn’t changed.
The practical starting point is a parts consumption report covering the last 12 months: which parts appear most frequently, which job types consume the most stock, and where the gap is widest between parts ordered and parts invoiced. That report already exists in most job management systems. Most businesses just don’t pull it.
This is where the connection to your broader data strategy moves from theoretical to operational. FTFR data tells you parts availability is contributing to return visits. Job history data tells you exactly which parts, for which job types, are driving the gap. You can’t get from “our first-time fix rate is below where it should be” to “here’s what needs to be on every van” without that second layer.
What the total picture adds up to
Take a 10-engineer field service business. One unnecessary return visit per engineer per week at £85 per visit costs around £44,000 a year in wasted labour and fuel alone. One merchant run per engineer per day at 45 minutes lost per run removes roughly 15% of each engineer’s productive time, which at a £45 charge-out rate across the team represents somewhere around £52,000 in capacity that’s being consumed by supply runs rather than billable work. Parts shrinkage and billing leakage on £100,000 of annual parts spend, using the conservative 5% figure, adds another £5,000 of cost that goes unrecovered.
That’s over £100,000 a year across three categories of loss, none of which appears on a P&L as “van stock problem.” It shows up as thinner margins, overtime, engineers who always seem to be running late, and job profitability figures that never quite match the quoted rate. And none of it requires anything to have gone catastrophically wrong. It’s just what happens when parts management runs on informal systems and individual habits rather than a consistent process.
How Fieldmotion supports stock management
Fieldmotion’s stock management module connects van inventory directly to the jobs that consume it. Parts get logged against jobs from the mobile app in the field, which means they appear on the invoice automatically and the stock count updates in real time. The office can see what’s on each van without calling the engineer, and reorder alerts trigger when levels drop below the thresholds the business sets.
Because stock is linked to job management rather than sitting in a separate system, the data that feeds van stock decisions: what parts were used on which jobs, which job types generate the highest parts consumption, which engineers are logging parts consistently and which aren’t, is visible in the same place the business already uses to run its operations.
For businesses where unlogged parts and billing leakage are the biggest problem, that connection between parts used and invoice generated is the most direct fix available. When fitting a part and charging for it happen in the same workflow, rather than as two separate steps that require someone to remember to link them, the gap closes.
Book Your Free Demo
Discover how our job management software can streamline your operations, reduce paperwork, and keep your field teams on track.
FAQs
How do I decide what should be on a standard van stock list?
Start with your job data from the last 12 months. Look at the parts that appear most frequently across the job types that make up the majority of your work, then set those as core stock. Parts that appear on fewer than one in ten jobs probably don’t belong on a standard list. They’re better ordered specifically for jobs where they’re needed. Review the list every quarter as your job mix evolves.
How much stock should each van carry?
There’s no universal figure, but a useful benchmark is to track your inventory-to-revenue ratio: the total value of stock on all vans divided by monthly revenue. Most well-run field service businesses target somewhere between 2% and 5%. Higher than that suggests overstocking. Lower suggests you’re likely running into availability problems more than the data is showing.
What’s the best way to handle parts that get used but not logged?
The process fix is to make logging parts the path of least resistance at job completion. If your engineer is already signing off a digital job sheet and collecting a customer signature, adding parts used to that same workflow takes seconds and becomes habit quickly. The management fix is to run a regular comparison between parts issued to vans and parts invoiced to customers. Any consistent gap in a specific engineer’s numbers is a conversation worth having.
How do I deal with engineers who are resistant to changing how they manage their vans?
Start with the data rather than the policy. If you can show an engineer that their van is currently carrying £3,000 of stock that hasn’t moved in six months, or that three specific jobs last quarter required return visits because a part wasn’t there, the conversation becomes practical rather than procedural. Most resistance to changing van stock management comes from engineers who don’t trust the replacement system to be better than the one they’ve built themselves. Demonstrating the reliability of the new process, consistently restocked, accurate counts, parts there when needed, wins that argument more effectively than anything else.
