If you’ve decided to train Mental Health First Aiders, you’ve already made a good decision. The question that tends to stall things next is how many Mental Health First Aiders you actually need.
It sounds like it should have a tidy answer. Physical first aid more or less does. Ask around about mental health first aid, though, and you’ll be told one per 50 staff, one per 10 staff, one per department, or “as many as you can afford.” They can’t all be right, and most of them are guesses dressed up as rules.
So here’s a straight answer to how many mental health first aiders you need, followed by a method for working it out that will hold up when someone in finance asks you to justify the number.
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Is There a Legal Requirement for Mental Health First Aiders?
No. There’s no UK law that says you must have Mental Health First Aiders, and no legal ratio to hit.
What does exist is a duty to carry out a first aid needs assessment, and the HSE now expects that assessment to take mental health into account alongside physical health. Its guidance says that, following your assessment, you might decide it’s beneficial to have people trained to recognise and support someone experiencing a mental health issue.
That’s a suggestion rather than a rule. But it does mean the number you land on should come out of an assessment you can point to, not a guess.
Is There an Official Ratio for How Many Mental Health First Aiders You Need?
No, there’s no official ratio for how many mental health first aiders you need.
MHFA England doesn’t publish one, nor does HSE. The figures you’ll see quoted around the internet (usually one MHFAider per 50 employees, sometimes one per 10) have been borrowed from older physical first aid guidance and repeated until they started to sound official.
That doesn’t make one per 50 a bad starting point. Plenty of organisations use it, and it’s a reasonable place to begin. Just don’t present it to leadership as though it’s a standard, because someone will eventually go looking for the source and won’t find one.
The better approach is to build your number from the workforce you’ve actually got.
How to Work Out How Many Mental Health First Aiders You Need
Start With Coverage, Not Headcount
The mistake most employers make is treating this as a maths problem based on total staff numbers. It isn’t. It’s a coverage problem.
A Mental Health First Aider is only useful to someone who can reach them, knows who they are, and feels comfortable approaching them. So the real question isn’t “how many people do we employ?” It’s “is there someone available, on every site and every shift, that a struggling colleague could realistically go to?” Answer that, and the number tends to work itself out.
Map Your Sites, Shifts and Remote Workers
A key factor in deciding how many mental health first aiders you need is simply the geography and logistics of it all. Run through the practicalities:
- Multiple sites. Every site needs its own cover. A brilliant MHFAider in head office is no help to the depot 80 miles away.
- Shift patterns. If you run nights or weekends, those shifts need cover too. This is where a lot of programmes fall short.
- Remote and hybrid staff. Home workers are often the people most in need of a check-in and the least likely to get one. Make sure at least one of your MHFAiders is accessible to them.
- Departments and teams. People rarely want to talk to someone they see every day about something personal. Spreading MHFAiders across different teams gives colleagues a choice.
- Who’s in your workforce. If a large part of your team shares a first language other than English, or works in a role with little contact with the rest of the business, factor that in too.
Factor In Your Risk Profile
Some workplaces carry more mental health risk than others, and the HSE’s own data reflects that. Work-related stress, depression or anxiety affected an estimated 964,000 workers in Great Britain in 2024/25, which was 52% of all work-related ill health (HSE, 2024/25). Rates are consistently higher in sectors such as health and social care, education, and public administration.
If you’re in one of those sectors, or your teams deal with the public, trauma, bereavement, safety-critical work or heavy shift patterns, plan for more cover than a low-risk office of the same size would need.
Allow for Real Life
Whatever number you settle on, add to it. MHFAiders go on holiday, take maternity or paternity leave, move departments, and leave the business. Certificates expire after three years too, so if you train everybody in one go, they’ll all fall due at once.
A programme built on two people is one resignation away from having none.
How Many Mental Health First Aiders You Need by Workforce Size
Below, we’ve created a table with a list of suggested ratios for how many mental health first aiders you need by workforce size. These numbers are based on practicality and generally realistic numbers, but only you know how your business works – use these figures as a jumping-off point.
| Workforce | Reasonable starting point | Also consider |
|---|---|---|
| Under 50 | 1 to 2 MHFAiders | Cover for absence and leavers |
| 50 to 500 | Roughly 1 MHFAider per 20 to 30 employees | One per site, spread across teams, shift cover |
| 500+ | Roughly 1 MHFAider per 50 to 100 employees, backed by a full needs assessment | A coordinator role, refresher schedule, formal network |
These bands mirror the guidance in our complete guide to Mental Health First Aid, so treat this as a conversation starter with your leadership team rather than a target. Your own assessment might land somewhere quite different, and that’s fine, as long as you can explain why.
Why the Number Isn’t the Whole Story
Once you’ve figured out how many mental health first aiders you need, you can train the “right” number of Mental Health First Aiders and still end up with a programme that does very little.
MHFAiders are there to spot the signs, listen and signpost. They aren’t therapists, and they shouldn’t be carrying the weight of your entire mental health provision. If there’s nowhere to signpost to, all you’ve done is give a group of well-meaning colleagues an impossible job.
Trained Managers
The support around your MHFAiders matters just as much as the number of them. Only 29% of organisations provide any training for managers specifically on supporting staff with mental ill health, according to the CIPD Health and Wellbeing at Work Report 2025. Of those that do, 73% report that their managers feel confident having sensitive conversations and signposting to appropriate support, against just 57% where no training has been given. Your MHFAiders can’t compensate for a manager who doesn’t know what to do next. If manager mental health training isn’t already part of your wider strategy, it’s worth putting alongside your MHFAider numbers on the same business case.
Somewhere to Refer To
An EAP, workplace counselling, occupational health, or all three. Make the referral routes obvious, both to your MHFAiders and to the colleagues they’re supporting.
Visibility
If staff don’t know who the MHFAiders are, the number is irrelevant. Photos on the intranet, posters in break rooms, a mention at induction. It doesn’t need to be elaborate, but it does need to happen.
Support for the MHFAiders Themselves
When determining how many mental health first aiders you need, it’s important to consider how many you can support, too.
Regular check-ins, clear boundaries, and a route to escalate. It’s exactly the same principle we set out in our guide to building a workplace wellbeing champions programme, and it applies just as much here.
How Often Should You Review the Number?
Once a year is a sensible time to review how many mental health first aiders you need. You should also revisit it whenever something changes: a new site, a restructure, a merger, a shift to hybrid working, or a spike in stress-related absence.
Keep a simple register of who’s trained and when their certificate expires. MHFA England certification lasts three years, and a refresher keeps people current without repeating the full two days. If you’ve only got one or two people falling due at a time, an open refresher course is usually the cheaper route.
Frequently Asked Questions About How Many Mental Health First Aiders Your Workplace Needs
Is there a legal requirement for how many Mental Health First Aiders you need in the UK?
No. There’s no UK law setting a required number or ratio. Employers do have a legal duty to carry out a first aid needs assessment, and current HSE guidance expects that assessment to consider mental health alongside physical health.
Is there an official ratio of Mental Health First Aiders to staff?
No official ratio exists. Figures such as one per 50 or one per 10 employees are commonly cited starting points, borrowed from physical first aid guidance, rather than rules set by the HSE or MHFA England.
How often should we review our number of Mental Health First Aiders?
Once a year as standard, and again whenever something changes significantly, such as a new site, a restructure, a shift to hybrid working, or a noticeable rise in stress-related absence.
The Short Version
There’s no magic ratio for how many mental health first aiders you need. Work out what proper coverage looks like across your sites, shifts and teams, add a bit of slack for real life, and build the wider support so your MHFAiders aren’t left holding everything on their own.
If you want more detail on what Mental Health First Aid involves before you commit, our complete guide to Mental Health First Aid in the workplace covers the courses, the role, and how to set the programme up properly. And if you’d rather talk it through with someone who’s done this a few hundred times, that’s what we’re here for.
We’ve been training workplace Mental Health First Aiders for years, across everything from small offices to multi-site manufacturers. Whether you want a private course for your team, a couple of places on an open course, or just a quick check-in on how many mental health first aiders you need, get in touch below.
