Venue Capacity Calculator for Martyn's Law
To work out your venue's capacity for Martyn's Law, find the greatest number of people reasonably expected on site at the same time, including staff, volunteers, and contractors. Use evidence you already hold: fire safety occupancy figures, attendance records, seat counts, ticket sales, or licence limits. Assess your busiest realistic day, not an average one. 200 to 799 people means standard tier. 800 or more means enhanced tier.
The free calculator below does the fire safety method for you, using Approved Document B floor space factors and exit width analysis.
New to Martyn's Law?
Start with our 5-minute guide.
Calculate Your Venue Capacity
Step 1: Choose Your Calculation Method
The Act accepts several methods for determining your expected numbers. This calculator supports the two most common.
Step 2: Add Your Room Zones
Divide your venue into zones by use type. Each zone uses a different occupancy density factor. Exclude stair enclosures, lifts, toilets, corridors, and plant rooms from the area.
Can't see your room type? Pick the closest match. That's what the official fire safety guidance says to do when a use isn't listed.
Step 3: Add Your Exits
Measure the clear opening width of each exit in millimetres. Your final capacity is the lower of the floor space figure and the exit figure.
Step 4: Add Staff Count
Martyn's Law capacity includes everyone on site: customers, staff, volunteers, and contractors. Enter the maximum number of staff you would expect on site at the same time during your busiest period.
How Does Capacity Work Under Martyn's Law?
Under the Terrorism (Protection of Premises) Act 2025, your capacity is the “greatest number of individuals reasonably expected to be present at the same time”. Everyone counts towards it: customers, staff, volunteers, and contractors. There's no strict mathematical formula. It's a judgement based on evidence you already hold.
The thresholds are straightforward. Under 200 people and you're out of scope. Between 200 and 799 puts you in the standard tier. 800 or more means enhanced tier.
For a detailed overview of what the law requires, see our complete guide to Martyn's Law compliance.
What Are the Six Accepted Assessment Methods?
The Home Office accepts six ways to evidence your capacity: fire safety occupancy figures, historical attendance records, counts of fixed seating or standing positions, ticket or registration sales, limits set by licences or other restrictions, and any other reasonable method you can justify. Most venues already hold at least one of these, so working out your number rarely needs new measurements at all.
The official GOV.UK factsheet lists each method. The Home Office's assessment guidance (Supplementary Document A, published alongside the statutory guidance on 15 April 2026) walks through worked examples of each.
- Fire safety occupancy figures: floor space density factors and exit capacity analysis (the lower of the two). This is what the calculator above uses.
- Historical attendance data: actual records of attendance (door counts, CCTV, manual counts) plus staff.
- Fixed seating or standing positions: count of seats and designated standing areas plus staff.
- Tickets and pre-registration: maximum tickets issued for any session. Staff are included only if not already counted in the ticket figure.
- Imposed restrictions: caps set by entertainment licences, planning conditions, or other regulatory limits plus staff.
- Other reasonable methods: EPOS transaction data, customer flow assessments, or any other reasonable evidence with justification.
The government is clear that venues should not need to pay consultants for this. It should be a straightforward self-assessment.
Floor Space Factors (Approved Document B, Table D1)
These are the standard occupancy densities from Building Regulations Approved Document B. Divide your usable floor area by the relevant factor to get the maximum number of people per zone.
| Room / Use Type | m² per Person |
|---|---|
| Standing spectator areas, bar areas within 2m of serving point | 0.3 |
| Dance floor, nightclub, pop concert, bar (no fixed seating) | 0.5 |
| Concourse or queuing area | 0.7 |
| Dining room, restaurant, lounge, meeting room, bar | 1.0 |
| Exhibition hall or studio | 1.5 |
| Shop (main sales area), hairdresser | 2.0 |
| Art gallery, museum, workshop | 5.0 |
| Office | 6.0 |
| Shop (furniture, appliances, wholesale) | 7.0 |
| Kitchen or library | 7.0 |
Source: Approved Document B, Volume 2. Exclude stair enclosures, lifts, toilets, corridors, and plant rooms from your area measurements.
How ready is your venue for Martyn's Law?
Get a personalised report showing exactly where your gaps are.
Take the free 60-second readiness checkHow Do Exit Widths Affect Capacity?
Your fire safety capacity is the lower of two figures: the floor space calculation and the exit width calculation. Even if your floor area could hold 500 people, narrow exits might limit you to 200.
| Door Clear Width | Maximum Persons |
|---|---|
| 750mm (minimum) | 100 |
| 850mm | 110 |
| 1,050mm | 200 |
| Over 1,050mm | 200 + 1 per additional 5mm |
Key rules
- Single exit: capacity capped at 60 persons regardless of door width.
- Inward-opening doors: capped at 60 persons unless held open during occupation.
- Discount the largest exit: assume it could be blocked. Calculate capacity using only the remaining exits.
- Minimum door width: 750mm (900mm where wheelchair users are expected).
What Does “From Time to Time” Mean?
“From time to time” means with some regularity, not as a one-off. Assess your peak use, not an average day: if your venue reaches 200 or more people on regular busy nights, weekend peaks, or seasonal events, it's in scope even if a normal day is much quieter.
The Home Office's own example is a pub that only passes 200 people at weekends. Those regular Friday and Saturday peaks put it in the standard tier. A single unexpected one-off doesn't trigger the duty. The same logic applies at the top of the band, and it bites harder there: a venue that expects 800 or more people on just a handful of event nights a year is enhanced tier premises.
Your Venue Is in Scope. What Next?
If the calculator shows you're in the standard tier (200-799), you need public protection procedures for four things: evacuation, invacuation, lockdown, and communication. Your staff and volunteers need to know these procedures.
Read our complete compliance guide for the full picture, or use Standard Tier to generate your PPP, train your staff and volunteers, and build an audit trail in 10 minutes.
30-day free trial · No card required · £18/month (usually £38), unlimited staff and volunteers after that
Frequently Asked Questions
How do I measure floor area for the calculator?
What if my venue has areas with different uses?
Why is the largest exit discounted?
What if my door opens inward?
Does capacity include staff?
Can I use a different method instead of floor space factors?
What if my venue goes over 200 only occasionally?
Official Sources
Stay ahead of Martyn's Law
Get compliance updates, practical advice, and free tools straight to your inbox. No spam, just the stuff that matters.
Unsubscribe any time. We won't share your email. Our Privacy Policy explains how we handle it.
Or take the 60-second readiness check to get a personalised report.
Last reviewed: 17 July 2026. Based on the Terrorism (Protection of Premises) Act 2025, Approved Document B, and the Home Office assessment guidance published on 15 April 2026. Floor space factors and exit width rules are from fire safety guidance and may not reflect your specific premises conditions.
This guide is general information about the Terrorism (Protection of Premises) Act 2025, not legal advice. Duties under the Act rest on the responsible person for each venue and cannot be transferred. If you're unsure how a specific requirement applies to your premises, take advice from a solicitor or qualified security adviser before acting on anything you read here.
Standard Tier is an independent platform and is not affiliated with the UK Home Office, the SIA, or any government body.