How to Calculate the Workforce Your PCN Actually Needs
- 1 day ago
- 6 min read
"Can you help me find the best practice staff ratios for a PCN? Something like how many Social Prescribers per 10,000 patients?"
This recent question inspired this latest blog, where we cover:
Why there's no universal ARRS staffing ratio—and why that's actually a good thing
The diagnostic questions to ask before you calculate WTE
Why taking the time to understand your network pays off
How to use demand-based modelling with your own data
How budget, demand, and assumptions work together
How to involve your practices so they're invested in the outcome
A tool that calculates a suggested WTE for your network
Here is our approach ⬇️
Stop Searching for PCN Workforce Ratios — Start Here Instead
It's tempting to search for a benchmark. A number you can point to that tells you exactly how many Clinical Pharmacists or Social Prescribing Link Workers your PCN should have. It feels like it would make things simpler.
But borrowing someone else's ratio is a shortcut that often leads you to the wrong destination.
The question "How many staff do we need?" assumes capacity is the problem. But what if it isn't?
You might already have the WTE you need, but if practices aren't referring, staff aren't working at the top of their licence, or the referral process is clunky, the question shifts from "How many ARRS staff does your PCN actually need?" to "Are we getting the most from what we've already got?"
Why taking time to understand your network matters
I know you're busy, and I understand the temptation to find a quick answer and move on, but rushing this creates problems down the line.
If you recruit based on a ratio you've borrowed from another network, or based on assumptions about what you can afford rather than what you actually need, you might end up with staff who don't have enough work because demand isn't there, or staff who are overwhelmed because you underestimated.
Either way, you're back to square one, but now with recruitment costs sunk and potentially a difficult conversation about whether roles are working.
Taking the time upfront to understand what your network actually needs means:
You recruit with confidence. You know the demand exists because you've measured it.
You can set realistic expectations. With practices and with the staff themselves. Everyone knows what success looks like.
You have evidence for difficult conversations. If your calculated WTE exceeds your budget, you've got data to support the discussion about priorities.
Practices are invested. When they've been part of working out what's needed, they're far more likely to refer appropriately and support the roles.
Staff feel valued. They're not walking into a role that was created based on a guess. They can see the need for their work.
Budget decisions become strategic, not reactive. You're choosing where to invest based on evidence, not just filling roles because you have allocation to spend.
This isn't about creating perfect plans. It's about making informed decisions rather than hopeful ones.
The diagnostic questions to ask first
Before we calculate WTE, we would want to establish:
What have we got in place now, and is it working?
What's going well? What isn't?
Have we spoken to the practices about how they're using these roles?
Have we spoken to the staff themselves about what's helping and hindering them?
What expectations have we set with practices and the staff members and are they realistic?
Does our internal referral process actually work, or does it need reviewing?
The answers to these questions require proper conversations. These conversations may also surface other issues, such as unclear pathways, limited awareness of which roles offer what, or mismatched expectations.
Once you've done that diagnostic work and you're confident the issue genuinely is capacity, then the question becomes practical demand-based workforce planning.
Demand-based modelling
Rather than asking "what do other PCNs do?", start with your own data:
How many consultations are needed each week for each role?
What's your average appointment length, initial and follow-up?
How many follow-ups does a typical patient journey involve?
What proportion of clinical time is actually patient-facing versus admin, MDTs, and travel?
If you don't have this data yet, this is your next job, and do this with your practices, not for them.
How to gather your data
Look back at your activity and decide together on the timeframe that makes sense. A full year might capture patterns and seasonal variation.
The last three months might be more relevant if things have shifted recently.
There's no universal right answer, but when practices are part of the process from the start, they're invested in what comes next. They're not just being told "we've calculated you need X" they helped work it out.
This collaborative approach has another benefit: it surfaces local knowledge.
Practices often know things that don't show up in the data. That context makes your modelling more accurate and helps further build your relationships with your practices.
Ask your practices, "what doesn't the appointment data tell us which is important for me to know"
Work backwards from demand
Example:
If a Social Prescribing Link Worker does 60-minute initial appointments and 30-minute follow-ups, and your average patient has two follow-ups, that's two hours per patient.
Also factor in realistic clinical contact time and annual leave to calculate how many appointments one WTE can manage per year.
Then compare that to your demand.
It's not complicated. It just requires you to know your own numbers rather than borrowing someone else's.
When budget and demand don't align
The reality: most PCNs aren't making recruitment decisions based purely on demand. Budget matters. Assumptions matter. The art is in bringing these together.
You might calculate that you need 2.5 WTE Dietitians based on demand, but your budget only stretches to 1 WTE. That's not a failure of the modelling, it's useful information.
Now you can have an honest conversation about what 1 WTE can realistically deliver, set expectations accordingly, and make a conscious choice about the gap.
The problem comes when PCNs work the other way round. They start with "we can afford 1 WTE" and assume that will be enough, without ever checking whether it matches demand.
Knowing your demand gives you options:
Prioritise differently. Maybe the Dietitian's need is greater than you realised, and you scale back elsewhere.
Set realistic expectations. If you can only fund half the capacity you need, practices need to know that referral criteria will be tighter.
Build a case for future investment. You've got evidence now. If demand significantly outstrips what you can afford, that's a conversation for your ICB or your next planning round.
Make assumptions explicit. When you document that you're funding 1 WTE against a calculated need of 2.5, everyone understands the trade-off. No one's pretending the gap doesn't exist.
The worst position is not knowing. If you've never calculated demand, you're making budget decisions based on assumptions, and you won't know whether those assumptions were right until problems emerge.
What good looks like
The goal isn't perfection, it's to make informed decisions and:
Recruit to a number you can justify
Set expectations that are realistic given your resource
Spot early if utilisation is too low or too high
Have evidence-based conversations about future investment
And yes, this tells you what you need. If you need more staff, recruitment is a separate challenge. But you can't solve a problem you haven't defined.
A tool to help
We built a workforce demand calculator that does exactly this.
You input your assumptions for each ARRS role, appointment lengths, follow-ups, and weekly demand, and it calculates a suggested WTE based on your specific situation.
Want to try it? There's a free version you can use right now to get a feel for how it works. It covers three key roles so you can test the approach with your own data.
PCN Members Club members get the full version, which includes:
All 25 ARRS-eligible roles across seven categories
Adjustable clinical contact time and DNA rates
Add your own custom roles
Save your work and return anytime
Download PDF and Excel reports for your board
Calculation breakdowns showing exactly how WTE is derived
No magic ratios. Just practical planning based on what's actually happening in your network.
We hope this helps!
About Us
THC Primary Care is an award-winning healthcare consultancy specialising in Primary Care Network Management and the creator of the Business of Healthcare Podcast. With over 20 years in the industry, we've supported more than 200 PCNs through interim management, training, and consultancy.
Our expertise spans project management and business development across both private and public sectors. Our work has been published in the London Journal of Primary Care, and we've authored over 250 blog posts sharing insights on primary care networks.
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