Occupancy calculator · Free · No sign-up
Occupancy Calculator
An occupancy calculator works out how many people a room may hold. Divide the floor area by the floor space factor for its use, check the result against what the exits can take, and the lower figure is the limit. This one does both, by UK or US rules, and also gives a hotel-style occupancy rate.
An estimate for planning, not a fire risk assessment. Nothing leaves this browser.
- Floor area allows
- 120
- Exits allow
- 110
- Exits counted
- 1 of 2
Enter how many are inside to see the share of the limit.
- Available
- 110
- Paid occupancy
- 72.7%
- Other convention
- 73.3%
The figures above are an example: replace them with yours. Everything is worked out in this browser and kept there. An estimate by the published method, not a fire risk assessment or a certified capacity. To count people in and out against the result, use the people counter.
Floor area gives one figure and the exits give another, and the rules decide both: a 750 mm door is 60 people under Approved Document B and 100 under the UK guide for existing premises. Pick the rules, enter the areas and the doors, and the lower figure is shown with what set it.
Maximum occupancy, or occupant load, is the most people a room or building is designed or assessed to hold at once. It is worked out from the floor area and its use, then limited by the number and width of the exits, so the smaller of the two figures applies.
- No sign-up
- Nothing sent anywhere
- UK and US rules
- Works offline
- Shows its working
Key facts
| Detail | Answer |
|---|---|
| Price | Free, no sign-up, nothing to install |
| Rule sets | Approved Document B volume 2 (England), the UK fire risk assessment guides for existing premises, and the 2024 International Building Code (US) |
| Floor space factors | Table D1 of Approved Document B in m² a person; IBC Table 1004.5 in ft² a person, gross or net |
| Exit widths | ADB Table 2.3; the guide’s 750 and 1050 mm figures by risk; IBC 0.2 inch a person for doors, 0.3 for stairs |
| Largest exit | Discounted under the UK rules; under the IBC, losing one exit must leave half the capacity |
| Exit count limits | UK: one exit up to 60 people, two up to 600 (ADB). US: one exit up to 49, three from 501, four from 1,001 |
| Rounding | Part people rounded down for a UK capacity, up for an IBC occupant load |
| Occupancy rate | Occupied ÷ available units over a period, out-of-order rooms in or out, paid occupancy shown |
| Units | m² and mm, or ft² and inches; switching never changes a result |
| Where figures are kept | This browser only |
| What it is not | A fire risk assessment, a building control approval or a licensed capacity |
How to work out a room’s maximum occupancy
Two calculations and the lower answer, the method UK fire services and the US code both use.
Pick the rules that apply
Approved Document B for a new or altered building in England, the fire risk assessment guide for existing UK premises, or the IBC 2024 in the US. For the guide, choose the premises’ risk level.
Enter each area by its use
Measure the floor in m² or ft² and choose what it is used for. Split a room with a bar, a dance floor and seating into separate areas; enter fixed seats as a count.
Enter every exit’s clear width
Measure the narrowest point of each way out of the room with the door open, not the frame, and add one row per exit.
Read the lower figure
The board shows the maximum and says whether the floor area or the exits set it. Under the UK rules the widest exit has already been taken away.
Check the room against it
Enter how many are inside to see the share of the limit, or count the door live with the people counter.
Confirm it before relying on it
Take the figure to your fire risk assessment, building control body or fire marshal. A calculator cannot see travel distances, stairs, alarms or who needs help to leave.
Who needs a maximum occupancy figure
Anyone deciding how many people a room can take, before the night rather than at the door.
Pubs, bars and clubs
A figure by zone, standing at the bar, the dance floor and the seating, checked against the doors, to set against the premises licence and the fire risk assessment.
Village and church halls
The number a hirer can be told, worked out the way fire service guidance for halls does it: floor area by use, then the exits.
Weddings and functions
A function room checked against the guest list before booking, laid out with tables at 1.0 m² a person rather than standing at 0.3.
Offices and coworking
Desks and meeting rooms at 6 m² or 150 gross ft² a person, with the exits checked when a floor is reorganised.
Shops and showrooms
Sales floor at 2 m², bulky goods at 7, and the queuing area at 0.7, each as its own row.
Hotels, hostels and campsites
The occupancy rate for a night, a month or a season, with out-of-order rooms handled the way your reports already do.
One door, three answers: how many people a fire exit can take
A 750 mm fire exit is 60 people in Approved Document B and 100 people in the government’s fire risk assessment guide, and both are current. They answer different questions. Approved Document B is the guidance for designing a new building, or a material alteration, to meet the Building Regulations in England. The fire risk assessment guides, published in 2006 and still on gov.uk, are for the responsible person assessing premises that already exist under the Regulatory Reform (Fire Safety) Order 2005, and they scale an exit’s capacity by how risky the premises are. The calculators in the search results use one table or the other without saying which.
| Clear width | Approved Document B | Guide, higher risk | Guide, normal risk | Guide, lower risk | IBC 2024 door (0.2 in) |
|---|---|---|---|---|---|
| 750 mm (29.5 in) | 60 | 80 | 100 | 120 | 147, under the 32 in minimum |
| 850 mm (33.5 in) | 110 | 80 | 100 | 120 | 167 |
| 900 mm (35.4 in) | 110 | 80 | 100 | 120 | 177 |
| 1050 mm (41.3 in) | 220 | 160 | 200 | 240 | 206 |
| 1200 mm (47.2 in) | 240 | 190 | 230 | 270 | 236 |
| 1500 mm (59.1 in) | 300 | 250 | 290 | 330 | 295 |
| 1800 mm (70.9 in) | 360 | 310 | 350 | 390 | 354 |
How each column is worked out
Approved Document B, Table 2.3. Up to 60 people need 750 mm, up to 110 need 850 mm, up to 220 need 1050 mm, and above that 5 mm a person. Widths under 1050 mm are not interpolated, so a 900 mm door counts as 850 mm: 110 people. The 5 mm rule does not apply to an opening serving fewer than 220, so 1050 to 1100 mm stays at 220.
The fire risk assessment guide, page 67. At least 750 mm takes up to 80, 100 or 120 people in higher, normal or lower risk premises; at least 1050 mm takes 160, 200 or 240; and 75 mm more is needed for each further 15 people. That is where the 290 for a 1500 mm door in some fire service guidance comes from: 200 plus six steps of 15. The guide gives no figure between 750 and 1050 mm, so the calculator holds the 750 mm figure until 1050.
The IBC, section 1005.3. Doors, corridors and ramps need 0.2 inch of width a person, stairs 0.3 inch, so a door’s capacity is its clear width in inches times five. A door must also be at least 32 inches clear (1010.1.1), which a 750 mm door is not. Some editions and local amendments allow lower factors in buildings with sprinklers throughout and an emergency voice/alarm system; the calculator uses the base factors, the cautious figure.
Which applies to you: in England, a new building or a material alteration is designed to Approved Document B (Wales and Scotland have their own documents); an existing pub, hall or shop is assessed by its responsible person, for which the guides are the government’s own method; a building in the US is held to whichever edition of the IBC, or a local code, the jurisdiction has adopted. The width is the clear width: the narrowest point of the way out with the door open, not the frame.
Sources: Approved Document B, volume 2 (2019 edition, with amendments to 2026), Table 2.3 and paragraphs 2.18 to 2.22; Fire safety risk assessment: offices and shops (2006), Part 2, page 67; 2024 International Building Code, chapter 10, sections 1005.3 and 1010.1.1; read 2026-10-25.
Floor space factors: how much floor each person is allowed
A floor space factor, which the IBC calls an occupant load factor, is the floor allowed for each person in a space of a given use. Divide the area by it and you have the number of people the space is planned for. The UK table works in square metres; the US one in square feet, and each US row says whether to divide the gross or the net area.
| Use | Table D1, m² a person | IBC 2024, ft² a person | The IBC figure in m² |
|---|---|---|---|
| Standing, or a bar within 2 m of the counter | 0.3 | 5 net, standing space | 0.46 |
| Assembly or dance hall, club, concert | 0.5 | 7 net, chairs only | 0.65 |
| Queuing area or concourse | 0.7 | 15 gross, airport waiting area | 1.39 |
| Restaurant, dining or meeting room | 1.0 | 15 net, tables and chairs | 1.39 |
| Exhibition hall, gallery or museum | 1.5 / 5.0 | 30 net | 2.79 |
| Shop sales floor | 2.0 | 60 gross | 5.57 |
| Office | 6.0 | 150 gross | 13.94 |
| Classroom | Not listed | 20 net | 1.86 |
| Kitchen | 7.0 | 200 gross, commercial kitchen | 18.58 |
| Library reading room | 7.0 | 50 net | 4.65 |
| Bedroom | 8.0 | 200 gross, residential | 18.58 |
| Storage, warehouse | 30 | 500 gross | 46.45 |
| Fixed seats | One a seat (Table D1, note 5) | One a seat (1004.6) |
Gross and net change the answer. Gross floor area is everything inside the walls, corridors, stairs, toilets, plant rooms and cupboards included; net is the space actually occupied, with those taken out. A 1,000 ft² restaurant with 250 ft² of kitchen, toilets and corridor is 50 people at 15 net ft² on its 750 ft² of dining floor, not 67. Some calculators still divide an office by 100 ft², the figure before the IBC’s 2018 edition; it is 150 gross in the 2024 table.
Three notes to Table D1 decide most real cases. Where one area has more than one use, apply the most onerous factor; where a building has different areas, work each out with its own factor and add them up, which is why the calculator takes one row per area. Instead of the table, a factor can come from actual data from similar premises at a peak trading time of year. And where people will normally be seated, the number can be the number of fixed seats. A part person is rounded down for a UK capacity, as fire services do in their worked examples, and up for an IBC occupant load, which sizes the exits: a part person still needs a way out.
Sources: Approved Document B, volume 2, Table D1 and its notes; the 2024 IBC Table 1004.5 values as listed by Allegion’s I Dig Hardware (6 April 2025); read 2026-10-25.
Exits: the widest is taken away, and one exit has a ceiling
Floor area says how many people a room is planned for. The exits say how many can get out, and the lower of the two is the maximum. Two further rules decide the exit figure, and they are where the UK and US part ways.
The widest exit is assumed to be lost
Approved Document B, paragraph 2.21: where there are several exits, fire might prevent one being used, so when using Table 2.3 “the largest exit should be discounted”, and the rest are added up (2.22). The fire risk assessment guide says the same for existing premises: assume “the widest is not available”, and if two exits are so close that one fire could block both, discount both. The IBC does not take an exit away. It requires instead that losing any one exit does not reduce the capacity below half of what is needed (1005.5), so the calculator caps the IBC figure at twice what the other exits can take.
One exit has a ceiling
| Exits | Approved Document B, Table 2.2 | Fire risk assessment guide | IBC 2024 |
|---|---|---|---|
| 1 | Up to 60 people | Up to 60, varied with the risk | Up to 49 in most groups (Table 1006.2.1) |
| 2 | Up to 600 | Above 60 | Up to 500 |
| 3 | More than 600 | Not set | 501 to 1,000 (1006.2.1.1) |
| 4 | More than 1,000 |
One room, three answers
A 200 m² (2,153 ft²) hall used for standing and dancing, with three exits of 1050, 850 and 850 mm:
| Rules | Floor area allows | Exits allow | Maximum | Set by |
|---|---|---|---|---|
| Approved Document B | 400 (0.5 m²) | 220: 1050 mm discounted, 110 + 110 | 220 | Exits |
| Guide, normal risk | 400 | 200: 1050 mm discounted, 100 + 100 | 200 | Exits |
| Guide, higher risk | 400 | 160: 80 + 80 | 160 | Exits |
| IBC 2024 | 431 (5 net ft², standing) | 540: 206 + 167 + 167 | 431 | Floor area |
The UK figures are set by the doors, and the cheapest way to raise them is usually the narrowest exit: widening both 850 mm doors to 1050 mm takes the Approved Document B figure from 220 to 400. Enter the hall in the calculator above and change one width at a time to see which door is holding the number down.
Sources: Approved Document B, volume 2, paragraphs 2.21 and 2.22 and Table 2.2; Fire safety risk assessment: offices and shops, pages 67 and 87 and the escape routes section; 2024 International Building Code, chapter 10, sections 1005.5, 1006.2.1 and 1006.2.1.1; read 2026-10-25.
Occupancy rate: the formula, and the out-of-order question
The other occupancy calculation is a rate: occupancy rate = units occupied ÷ units available × 100, for the same period. For a hotel the units are room-nights, so 120 rooms over a 30-night month are 3,600 room-nights available. The same formula works for beds in a hostel or ward, seats on a course, pitches on a campsite or desks in an office.
The figure people disagree about is the bottom of the fraction. Most hotel guides take rooms that are out of order out of what was available, because they could not be sold; others keep every room in the base, so that one month compares with the next whatever was being repaired. A hotel with 120 rooms, 10 out of order and 88 occupied, 8 of them complimentary:
| Convention | Working | Occupancy |
|---|---|---|
| Out of order taken out | 88 ÷ (120 − 10) | 80.0% |
| Every room kept in | 88 ÷ 120 | 73.3% |
| Paid only, out of order taken out | 80 ÷ 110 | 72.7% |
The calculator shows the convention you chose on the board and the other one beside it, with the paid-only rate, so a number you report can say what it counts. Two cautions: occupancy alone says nothing about price, which is why hotels pair it with average daily rate and revenue per available room; and a rate over 100% means the figures are wrong, usually because the occupied count covers more nights than the period entered.
What this calculator is not
This calculator works out an estimate by the published method. It is not a fire risk assessment, a building control approval or a licensed capacity, and it must not be used as one. In the UK the figure that applies comes from the fire risk assessment that the responsible person for the premises must carry out, and from any condition on a premises licence; in the US it is the occupant load approved by the building official and posted in the room. If those exist, they win.
| It does | It does not |
|---|---|
| Divide each area by the published factor for its use | Decide what your room is used for, or measure it |
| Work out what each exit can take from its clear width | Check travel distances, dead ends or inner rooms |
| Discount the widest exit, or apply the IBC half rule | Check stairs, final exits or exits shared between rooms |
| Apply the one-exit and exit-count limits | Allow for alarms, lighting, signs, sprinklers or fire doors |
| Show which figure sets the limit | Plan for people who need help to leave |
| Keep what you enter in this browser | Send it anywhere, or store it on a server |
The floor area figure also ignores furniture you add later: a hall worked out as an assembly hall without seating (0.5 m²) and then laid with tables is a dining room (1.0 m²), at twice the area a person. Work it out again whenever the use changes, and take anything you will rely on to a competent fire risk assessor, your building control body or the fire marshal.
Calculator, fire risk assessment, posted figure or spreadsheet
A capacity figure can come from several places. They differ in who stands behind the number.
| This calculator | A fire risk assessment | The posted or licensed figure | A spreadsheet | |
|---|---|---|---|---|
| Cost | Free | Free if you do it, a fee from an assessor | Already set | Your time |
| Binding | No, an estimate | Yes, it is the assessment | Yes | No |
| Floor area by use | Yes, three rule sets | Yes | Already applied | If you build it |
| Exit widths and discounting | Yes | Yes | Already applied | If you build it |
| Travel distance, stairs, alarms | No | Yes | Already applied | Rarely |
| Says which figure is the limit | Yes | Yes | No | Only if you add it |
| Time | Minutes | Hours to days | None | An hour or so |
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Frequently asked questions
How do you calculate the maximum occupancy of a room?
Divide the usable floor area by the floor space factor for the room’s use, such as 1.0 m² a person for a restaurant under Approved Document B or 15 net ft² under the IBC. Then work out how many people the exits can take. The maximum occupancy is the lower of the two figures.
How many square feet per person is needed for occupancy?
It depends on the use. Under the 2024 IBC it is 5 net square feet a person for standing space, 7 for chairs only, 15 for tables and chairs, 20 for classrooms, 60 gross for a shop floor and 150 gross for offices. The UK’s Table D1 works in square metres, from 0.3 standing to 30 for storage.
What is an occupant load factor?
The floor area allowed for each person in a space of a given use. Dividing a room’s area by it gives the occupant load, the number of people the space is planned for. The IBC lists occupant load factors in Table 1004.5; Approved Document B calls them floor space factors, in Table D1.
How many people can a fire exit door take?
It depends on its clear width and the rules. Under Approved Document B a 750 mm exit serves 60 people, 850 mm 110 and 1050 mm 220, then 5 mm a person. The UK guide for existing premises gives 750 mm 100 people at normal risk. The IBC allows 0.2 inch of door width a person.
Why is the largest exit discounted?
Because a fire could start beside it and block it. UK guidance assumes the widest exit cannot be used and checks that the others can still take everyone. The IBC does it differently: losing any one exit must not reduce the capacity below half of what is required.
How many exits does a room need?
Under Approved Document B, one exit serves up to 60 people, two up to 600 and three above that; the UK guides for existing premises also want two above 60. Under the IBC, a space with one exit is limited to 49 in most occupancy groups, with three exits from 501 people and four from 1,001.
How do you calculate an occupancy rate?
Divide the units occupied by the units available over the same period and multiply by 100. For a hotel that is room-nights occupied over room-nights available: 88 occupied of 110 available is 80%. Over a month, rooms times nights gives the available figure, so 120 rooms over 30 nights is 3,600.
Should out-of-order rooms be included in the occupancy rate?
Conventions differ, which is why the calculator shows both. Most hotel guides take out-of-order rooms out of what was available, so 88 of 110 is 80%. Others keep every room in the base so months compare consistently, giving 88 of 120, 73.3%. Say which you used when you report it.
Is the figure from this calculator my legal capacity?
No. In the UK the figure that counts comes from the fire risk assessment the responsible person must carry out, and any premises licence condition; in the US it is the occupant load the building official approves and posts. This calculator gives an estimate by the published method, to plan or check with.
What is the difference between gross and net floor area?
Gross floor area is everything inside the walls, including corridors, stairs, toilets, plant rooms and cupboards. Net floor area is only the space actually occupied, with those taken out. Each row of IBC Table 1004.5 says which to divide, and using the wrong one can change the answer by a third or more.
Related guides
Longer answers to the questions behind the numbers.