NCC D2D18 Explained: Number of Persons Accommodated and Table D2D18 Area per Person (2025 Guide)

Almost every egress and sanitary rule in Volume One of the National Construction Code (NCC) starts from one number: how many people the storey is assessed for. Clause D2D18 is where that number comes from. Table D2D18 is the list of square metres per person it is read from. This guide sets out the clause sub-clause by sub-clause and reproduces the table and the New South Wales version of it. It works through an office floor and lists every clause that then uses the number. The calculator in section 5 runs the method for your storey.

In one minute

• Three ways to get the number. You may divide the floor area of each part of the storey by the Table D2D18 figure for its use. Or you may take the seating capacity of an assembly building or room, or use any other suitable means of assessing capacity (D2D18(1)). The area method is the one used on nearly every project.

• Not all floor area counts. The area method excludes spaces set aside for lifts, stairways, ramps, escalators, corridors, hallways, lobbies and the like. It also excludes spaces set aside for service ducts, sanitary compartments and other ancillary uses (D2D18(1)(a)(i) and (ii)).

• The table runs from 0.3 m² to 50 m² per person. A standing spectator area is 0.3 m², and a bar standing area or dance floor 0.5 m². A cafe, restaurant, theatre or public hall is 1 m², and a classroom or board room 2 m². A shop is 3 or 5 m² and an office 10 m². Storage or a carpark is 30 m², and factory fabrication space 50 m².

• The number then drives the exits. A Class 9 storey or mezzanine with more than 50 persons needs two exits (D2D3(4)(a)(vi)). Over 100 persons, the aggregate exit width grows (D2D8(2) and (3)). Sanitary facilities are counted from the same number (F4D3(1)).

• Nothing changed in NCC 2025. The clause and every row of the table, national and NSW, are the same as NCC 2022 Amendment 2.

1. What D2D18 says, sub-clause by sub-clause

D2D18 sits in Part D2, Provision for escape, and opens with its scope. The number of persons accommodated in a storey, room or mezzanine must be determined with consideration to the purpose for which it is used and the layout of the floor area (D2D18(1)). That rule applies for the purposes of the Deemed-to-Satisfy Provisions.

Two things in that rule matter. It is a Deemed-to-Satisfy number, so a Performance Solution may justify a different one. And it is assessed per storey, room or mezzanine, which is the unit every downstream clause works in.

The clause then gives three methods, joined by "or".

• Method (a), the area method. Divide the floor area of each part of the storey by the number of square metres per person listed in Table D2D18 according to the use of that part. Then add the results together (D2D18(1)(a)). The division is done part by part. So a floor with an office area and a board room is two divisions added together, not one. Spaces set aside for lifts, stairways, ramps and escalators, corridors, hallways, lobbies and the like are excluded (D2D18(1)(a)(i)). So are service ducts and the like, sanitary compartments or other ancillary uses (D2D18(1)(a)(ii)).

• Method (b), the seating count. Reference to the seating capacity in an assembly building or room (D2D18(1)(b)). A theatre with 420 fixed seats is assessed for 420 in the auditorium, whatever the area method would give. The table itself says "per number of seats" for fixed spectator seating.

• Method (c), any other suitable means. Any other suitable means of assessing its capacity (D2D18(1)(c)). This is the relief for a use the table does not fit. One example is a fixed-plant factory floor, where the table says the area per person is determined by the use of the plant or equipment. Another is a room whose fit-out fixes how many people can be in it. The certifier decides whether the means is suitable, so the basis is documented, not assumed.

D2D18 has no figure and no second sub-clause. The table carries one note. Bar standing is an area used by the standing patrons. It extends not less than 1.5 m wide from the outside edge of the bar top, for the length of the serving area of the bar. That 1.5 m strip is assessed at 0.5 m² per person and the rest of the bar at 1 m².

2. Table D2D18 in full

The national table is reproduced below, row for row. Entries that are not a number are shown as the Code writes them.

Type of use	Area per person	Type of use	Area per person
Art gallery, exhibition area, museum	4 m²	Reading room	2 m²
Bar — standing	0.5 m²	Restaurant	1 m²
Bar — other	1 m²	School — general classroom	2 m²
Board room	2 m²	School — multi-purpose hall	1 m²
Boarding house	15 m²	School — staff room	10 m²
Cafe, church, dining room	1 m²	School — trade and practical area — primary	4 m²
Carpark	30 m²	School — trade and practical area — secondary	As for workshop
Computer room	25 m²	Shop — space for sale of goods — at a level entered direct from the open air or any lower level	3 m²
Court room — judicial area	10 m²	Shop — space for sale of goods — all other levels	5 m²
Court room — public seating	1 m²	Showroom — display area, covered mall or arcade	5 m²
Dance floor	0.5 m²	Skating rink, based on rink area	1.5 m²
Dormitory	5 m²	Spectator stand, audience viewing area — standing viewing area	0.3 m²
Early childhood centre	4 m²	Spectator stand, audience viewing area — removable seating	1 m²
Factory — machine shop, fitting shop or like place for cutting, grading, finishing or fitting of metals or glass, except in the fabrication of structural steelwork or manufacture of vehicles or bulky products	5 m²	Spectator stand, audience viewing area — fixed seating	Per number of seats
Factory — areas used for fabrication and processing other than a machine shop, fitting shop or the like	50 m²	Spectator stand, audience viewing area — bench seating	450 mm/person
Factory — a space in which the layout and natural use of fixed plant or equipment determines the number of persons who will occupy the space during working hours	Area per person determined by the use of the plant or equipment	Storage space	30 m²
Gymnasium	3 m²	Swimming pool, based on pool area	1.5 m²
Hostel, hotel, motel, guest house	15 m²	Switch room, transformer room	30 m²
Indoor sports stadium — arena	10 m²	Telephone exchange — private	30 m²
Kiosk	1 m²	Theatre and public hall	1 m²
Kitchen, laboratory, laundry	10 m²	Theatre dressing room	4 m²
Library — reading space	2 m²	Transport terminal	2 m²
Library — storage space	30 m²	Workshop — for maintenance staff	30 m²
Office, including one for typewriting or document copying	10 m²	Workshop — for manufacturing processes	As for factory
Patient care areas	10 m²
Plant room — ventilation, electrical or other service units	30 m²
Plant room — boilers or power plant	50 m²

NCC 2025 Volume One Table D2D18, Area per person according to use, national text. Note: bar standing is an area used by the standing patrons and extends not less than 1.5 m wide from the outside edge of the bar top for the length of the serving area of the bar. Reproduced under CC BY 4.0; attribution in section 10.

The spread is the point. The same 700 m² is 1,400 people as a dance floor, 700 as a restaurant, 234 as a ground-floor shop, 70 as an office and 24 as a store. The figure is a design density for egress and facilities, not a forecast of headcount. An office with 70 desks on 700 m² is assessed for 70, whether 40 or 90 people turn up. A bar is assessed as if every square metre of standing area were full.

3. What counts and what is excluded

The exclusions are the part of the clause most often applied loosely, in both directions (D2D18(1)(a)). The list is specific: lifts, stairways, ramps and escalators, corridors, hallways, lobbies and the like; service ducts and the like, sanitary compartments or other ancillary uses. A lift lobby, a fire stair, an escalator void, a corridor to the tenancies, a riser cupboard and every toilet are out.

A tea point, a store room and a plant room are not corridors or sanitary compartments. The table gives them their own rows (kitchen 10 m², storage 30 m², plant room 30 or 50 m²). So they are counted at those densities rather than left out. "Other ancillary uses" is the only open phrase. The safe reading is a space ancillary in the same way a duct or a toilet is, not a space that happens to be small.

Two points of practice. First, "set aside for" means the space is planned for that purpose. So a corridor formed by workstation layout on an open floor is still open office, not corridor.

Second, the exclusion runs one way. Leaving out the core reduces the number. Nothing in D2D18 lets you add an allowance back for a lobby that fills with people. That is because the downstream clauses already assume the whole storey evacuates at once.

4. Worked example: an 850 m² office floor

A tenancy floor has a gross floor area of 850 m². Of that, 120 m² is corridors and lift lobby and 30 m² is sanitary compartments. The rest is open office. The area method runs as follows.

Step	Reading	Result
Gross floor area	Measured on plan	850 m²
Exclude corridors and lobby	D2D18(1)(a)(i)	less 120 m²
Exclude sanitary compartments	D2D18(1)(a)(ii)	less 30 m²
Floor area to count	850 − 120 − 30	700 m²
Area per person	Table D2D18, office	10 m²
Persons accommodated	700 ÷ 10	70 persons
Exit width	70 is not more than 100	Each required exit and path of travel at least 1 m (D2D8(1))
Number of exits	Class 5, so D2D3(4) does not apply	Set by D2D3(1) to (3) and the travel distances in D2D5, not by the occupant number
Sanitary facilities	F4D3(1), (2)	Counted for 70 persons, 35 male and 35 female

The area method for one office floor. Had the whole 850 m² been divided, the answer would have been 85; the exclusions are worth 15 persons on this floor.

Two variations show how the method bends. First, say 60 m² of that open floor is fitted out as a board room. That part is divided by 2 m² instead of 10 m². So 640 ÷ 10 plus 60 ÷ 2 is 64 plus 30, and the floor is now assessed for 94 persons.

Second, the division may leave a fraction. The Code does not say what to do with it. The app's calculator and the one below round up, because a part of a person still needs an exit. That is the reading a certifier will expect.

5. Work out your own storey

Choose the use, then set the gross floor area and the share of it that is excluded. Tick Class 9 if the D2D3(4) two-exit trigger applies to the building. The headline gives the persons accommodated. The cards give the area counted, the rounding and the number of exits. They also give the exit width for that number under D2D8, the sanitary basis under F4D3 and the other thresholds the number crosses, each with its clause.

The same method is in the free occupancy and exits calculator. It has every row of the table, the D2D8 width check against what you provide and a printable receipt.

6. The New South Wales table

New South Wales replaces Table D2D18 with its own version (NSW Table D2D18). Every national row is carried across at the same figure. The difference is a set of rows for entertainment and performance uses. NSW defines and regulates these as entertainment venues in its other Part D2 variations.

Row added in NSW Table D2D18	Area per person
Auditorium — bench seating	450 mm/person
Auditorium — fixed seating	count seats
Auditorium — removable seating	1 m²
Auditorium — standing area	0.5 m²
Entertainment venue — other than auditorium	1.2 m²
Small live music or arts venue — dance floor	0.5 m²
Small live music or arts venue — information and education facility	4 m²
Small live music or arts venue — other	1 m²

NSW Table D2D18, rows not in the national table. The NSW table also omits the national row "Theatre and public hall, 1 m²"; a theatre in NSW is assessed on the auditorium rows instead.

Two NSW variations use the number the table produces. NSW D2D3(4) adds a seventh trigger for two exits: any storey or mezzanine within an auditorium in an entertainment venue. It sits alongside the national 50-person trigger.

NSW D2D8(5) replaces the national width formulas for a Class 9b entertainment venue. It uses 2 m plus 500 mm for every 50 persons or part in excess of 200. Merged paths of travel are at least as wide as the sum of the paths that merge.

NSW adopts NCC 2025 on 1 May 2027, and the NSW table is the same in NCC 2022. So the figures above apply there on either edition.

7. Where the number goes next

D2D18 does nothing by itself. Its number is called up by name in a dozen other clauses. Reading them together is the reason the number is worth getting right at sketch design. The ones that matter most are the exits and the sanitary count. The rest are thresholds that switch on at 100, 200 or 500 persons.

Clause	What the D2D18 number decides
D2D3(4)(a)(vi)	In a Class 9 building, any storey or mezzanine that accommodates more than 50 persons must have at least 2 exits in addition to any horizontal exit. D2D3(4)(b) relieves a plant room, machinery room, storeroom or the like with direct egress to a road, open space or a fire-isolated exit and a single exit that satisfies D2D5.
D2D8(2), (3), (4) via D2D11(1)(b)	Aggregate unobstructed width of the required exits, doorways excepted: 1 m plus 250 mm for each 25 persons or part over 100 (D2D8(2)); 2 m plus 500 mm for every 60 persons or part over 200 where egress uses a stair or ramp steeper than 1:12, otherwise for every 75 (D2D8(3)); 17 m plus the excess over 2,000 divided by 600 in an open spectator stand (D2D8(4)). At 100 persons or fewer only the 1 m floor in D2D8(1) applies. A doorway may be 250 mm narrower than the exit it serves (D2D9).
D2D15(5), (6), (7)	Discharge from exits: a required stair or ramp in an open spectator stand over 500 persons must not discharge to the ground in front of the stand; in a building with an auditorium over 500 persons not more than two-thirds of the required exit width may be in the main entrance foyer.
D2D16(4)	A horizontal exit needs a clear area on the far side of the fire wall of 2.5 m² per patient or resident in a Class 9a or 9c building and 0.5 m² per person elsewhere, for the total number served.
D3D26(5)	In a Class 9b building (other than a school, an early childhood centre or a building used for religious purposes), a door in a required exit serving a storey or room of more than 100 persons must open without a key by a single push on a device such as a panic bar between 900 mm and 1.2 m from the floor.
D4D8(3)	The number of hearing augmentation receivers where an inbuilt amplification system is installed is scaled to the persons accommodated in the room.
E3D7(1)(b)	A stairway platform lift must not serve a space accommodating more than 100 persons.
F4D3(1), (2)	Sanitary facilities are calculated for the D2D18 number unless it can be more accurately determined by other means, on the basis of equal numbers of males and females unless the premises are used predominantly by one sex. The companion guide, NCC sanitary facilities: F4D4 pans and basins, takes it from there.
F4D12(3)	Design occupancy for an accessible adult change facility, excluding staff-only areas and areas exempt under D4D5.
F5D2(5), (6)	Room height in a Class 9b building: 2.4 m for an assembly room or corridor serving not more than 100 persons, 2.7 m over 100.
S5C7(1)	The mezzanine concession on fire resistance is withdrawn for a Class 9b spectator stand or audience viewing area over 100 persons.

Volume One clauses that call up D2D18 by name. The glossary definition of building complexity criteria and the explanatory note to A6G1 also use it; Part I3 keeps only method (c) for a farm shed.

The 100-person line is the one to watch on assembly buildings. Crossing it changes the door hardware, the room height, the lift type and the exit width formula at once. On a hall assessed at 1 m² per person, the difference between 99 and 101 is 2 m² of floor.

8. Did D2D18 change between NCC 2022 and NCC 2025?

No. The clause text of D2D18 in NCC 2025 Volume One (version 1.2) is word for word the text of NCC 2022 Amendment 2. Table D2D18 is the same row for row, in both the national table and the NSW replacement. The comparison for this guide was made against the NCC 2022 Amendment 2 dataset the AEC Assistant occupancy calculator was transcribed from. That dataset records that the table carried no Amendment 2 tracked changes either.

In NCC 2019 the clause was numbered D1.13. The 2022 restructure renamed it without changing the method. The stair, handrail and other Part D3 rules that go with an exit are set out in the NCC stair requirements guide.

Which edition applies depends on where the building is. NCC 2025 applies from 1 May 2026 in the Commonwealth, the ACT, Tasmania, Victoria and Western Australia. It applies from 1 May 2027 in New South Wales, Queensland and South Australia. The Northern Territory has not adopted it.

For D2D18 the distinction is academic, because the answer is the same on either edition. But the dates matter for the clauses around it. They are set out in NCC 2025 changes and state adoption dates.

9. Common mistakes

• Dividing the gross floor area. The core, the corridors and the toilets come out first (D2D18(1)(a)(i), (ii)). On a typical office floor that is 15 to 20 per cent of the area. It is the difference between 85 and 70 persons on the example above.

• One density for the whole floor. The clause says each part of the storey, according to the use of that part. A board room, a training room or a staff cafe inside an office tenancy is divided by its own row. At 1 or 2 m² per person, a small room adds a lot of people.

• Reading "any other suitable means" as a discount. Method (c) is for a use the table does not fit, with the basis documented. Reducing an office from 70 to 40 because the tenant has 40 desks is a headcount, not an assessment of capacity. And the fit-out will change.

• Applying the 50-person exit trigger to a Class 5 or 6 building. D2D3(4) is the Class 9 sub-clause. An office or shop storey is not required to have two exits by its occupant number. Effective height, basements and D2D5 travel distances decide that. But the number still sets the width under D2D8.

• Forgetting the width formula starts at 101. Under 100 persons every required exit is 1 m. At 101 the aggregate becomes 1.25 m, and at 201 it becomes 2.5 m. Check the number against the D2D8 bands before the exit widths are fixed on plan.

• Using the national theatre row in New South Wales. NSW Table D2D18 has no "Theatre and public hall" row. The auditorium and entertainment venue rows apply. NSW D2D8(5) also sets a different width formula for an entertainment venue.

10. Where to read the source

NCC 2025 Volume One is on the NCC website, free to read. The clauses for this guide are:

• Part D2 Provision for escape: D2D18 and Table D2D18, with the NSW variation.

• D2D3 for the number of exits.

• D2D8 and D2D11 for exit width.

• D2D9 for doorways.

• F4D3 for the sanitary count.

Inside AEC Assistant the Code text is searchable by clause on every plan. So a question such as "how many persons is a 700 m² office floor assessed for" comes back with the table row and the clauses that use the number.

Sources: NCC 2025 Volume One (version 1.2) D2D18 and Table D2D18 including the NSW replacement table, D2D3, D2D8, D2D9, D2D11, D2D15, D2D16, D3D26, D4D8, E3D7, F4D3, F4D12, F5D2 and S5C7. These were checked against the published text on 21 September 2026. NCC 2022 Volume One Amendment 2 D2D18 and Table D2D18 for the edition comparison. Table D2D18 and the NSW rows are reproduced under the Creative Commons Attribution 4.0 International licence (CC BY 4.0). They are from NCC 2025 Volume One, © Commonwealth of Australia and the States and Territories of Australia, published by the Australian Building Codes Board. Diagrams by AEC Assistant. This article is general guidance. The building surveyor or certifier for your project determines compliance.