If you rent, buy or have a valuation done on an office or commercial property, you'll run into abbreviations like GFA, NLA and usable floor area within the first five minutes. They appear in the brochure, in the lease and in the valuation report, and all three mean something different. Mix them up and you're comparing apples with oranges — in the worst case, paying rent for years on square metres you can't actually use. This article explains what the terms mean, how they are measured under the Dutch measurement standard NEN 2580 (the Netherlands' national standard for measuring the areas and volumes of buildings), and how to use them in practice, with a worked example.
What is GFA (gross floor area)?
The gross floor area (GFA) is the total floor area of a building or storey, measured at floor level along the outer face of the external walls. Everything within that outline counts: the walls themselves, columns, stairwells, lift shafts, service shafts, corridors, toilets and plant rooms. For multi-storey buildings, you add up the GFA per floor.
GFA is the measure used by the construction sector, municipalities and valuers: for construction costs per m², for the zoning plan (omgevingsplan — the maximum buildable area on a plot under Dutch planning law), for the WOZ property value (the Dutch municipal property valuation used for local tax purposes) and for the energy label obligation. The requirement of a minimum energy label C for offices, for example, applies from 100 m² of usable floor area, not GFA, which immediately shows how important it is to use the right term. You can read more about that obligation in our article on the energy label for commercial properties.
What is NLA (net lettable area)?
The net lettable area (NLA) is the area a tenant can actually use and which usually forms the basis for the rent calculation. NEN 2580 defines it as the area measured at floor level between the partitions enclosing the space, subject to a number of exceptions. The NLA does not include:
- spaces with a clear height of less than 1.5 m;
- stairwells, lift shafts and other vertical circulation areas larger than 4 m²;
- plant rooms, such as space for the boiler or air handling units;
- load-bearing internal walls, columns and service shafts larger than 0.5 m²;
- the external walls themselves.
The NLA does include horizontal circulation areas (corridors), non-load-bearing partition walls, kitchenettes and toilet groups on the floor. For windows, the glass-line correction applies: if the windowsill is lower than 1.5 m, you measure to the glass line rather than to the inside face of the wall. On a façade with a lot of glazing, this can easily account for a few percentage points.
In a multi-tenant building, the NLA of common areas (entrance, reception, shared corridors) is usually apportioned pro rata among tenants. Your lease will then show your own NLA plus a share of the common areas. Read this carefully: you pay rent on the total.
What are net floor area, usable floor area and tare area?
Besides GFA and NLA, NEN 2580 defines a few other measures you'll come across:
- Net floor area (NVO): the GFA minus the construction: external walls, load-bearing internal walls, columns and shafts. Everything that remains as "floor".
- Tare area (structural area): the difference between GFA and net floor area, i.e. the area taken up by the construction itself. For offices, typically 5 to 10% of the GFA, more in older buildings with thick walls.
- Usable floor area (GO or GBO): the measure used for housing and for part of Dutch building regulations. Measured within the walls, excluding spaces lower than 1.5 m, stairwell openings, shafts larger than 0.5 m² and load-bearing walls. Usable floor area and NLA are close but not identical: usable floor area, for example, does include plant rooms.
- Efficiency ratio: the NLA/GFA ratio. The higher it is, the more efficient the building. For modern offices, the efficiency ratio is usually between 0.80 and 0.90; a listed canal-house building with thick walls and many staircases sits well below that.
Why does NEN 2580 matter?
NEN 2580 is the Dutch standard for measuring the areas and volumes of buildings. The standard specifies precisely where you measure, what you include and what you leave out. Without a shared standard, every landlord could define their own square metres. A NEN 2580 measurement report is therefore used by estate agents, valuers, banks and in most ROZ lease agreements (standard lease contracts published by the Dutch Real Estate Council, ROZ). There are two types:
- Type A measurement report: measured from (construction) drawings. Faster and cheaper, but dependent on the accuracy of the drawings.
- Type B measurement report: measured on site. More accurate, and the standard for sales, valuations and larger lease transactions.
As a tenant, always ask for the measurement report and check that the NLA in the lease matches it. A difference of a few per cent may look small, but it adds up over a five-year lease term.
Worked example: from GFA to NLA
Say you're looking at an office building with three storeys and external dimensions of 30 by 20 metres.
- GFA: 30 × 20 = 600 m² per floor, so 1,800 m² for the whole building.
- Tare area: external walls, columns and shafts take up roughly 40 m² per floor (around 7%). That puts the net floor area at 560 m² per floor, 1,680 m² in total.
- Exclusions for the NLA: per floor, a 20 m² stairwell, a 6 m² lift shaft and, on the ground floor, a 25 m² plant room. That's 3 × 26 + 25 = 103 m².
- Glass-line correction: the façade has low windowsills; the correction adds roughly 8 m² per floor, 24 m² in total.
- NLA: 1,680 − 103 − 24 = approximately 1,550 m².
The efficiency ratio is then 1,550 / 1,800 = 0.86. If this building is advertised at "€ 180 per m² per year", it makes a big difference whether that's based on GFA or NLA: 1,800 × 180 = € 324,000 versus 1,550 × 180 = € 279,000 per year. For lettings, NLA is the standard basis; if the listing states otherwise, ask for clarification. You can read more about how rents per m² are built up in what does office space cost per m².
Calculating GFA yourself
For a first indication, you can estimate the GFA yourself:
- Measure or read off the building's external dimensions per floor (length × width along the outside of the façade). For an irregular floor plan, divide the building into rectangles.
- Add up the areas of all floors, including basements and attics with a clear height of at least 1.5 m.
- Leave out external areas such as balconies, canopies and loading platforms; these are measured separately.
Estimating the NLA is harder, because you need to know the construction and the shafts. Use the efficiency ratio as a rule of thumb (0.80 to 0.90 for offices) or, better, the measurement report.
Which measure do you use when?
| Situation | Standard measure | Why |
|---|---|---|
| Rent for office or commercial space | NLA | You pay for what you can actually use |
| Construction costs, zoning plan, building permit | GFA | The full building volume counts |
| Energy label obligation for offices, Bbl requirements (Dutch Building and Living Environment Decree) | Usable floor area | Statutory threshold of 100 m² usable floor area |
| Housing (sale, WOZ) | Usable floor area (GO/GBO) | Measurement instruction for housing |
| Valuation and financing | NLA and GFA | Banks and valuers want to see both |
| Office units and flex offices | Often all-in per unit or workstation | Price per month, not per m² |
Common mistakes
- Comparing rents on different measurement bases. Building A is advertised at € 175 per m² NLA, building B at € 160 per m² GFA. Convert B to NLA and it's suddenly more expensive.
- Forgetting common areas. A share of the entrance and corridors can be 5 to 15% of your rental basis.
- Treating usable floor area and NLA as the same. They are close, but statutory thresholds such as the energy label obligation are based on usable floor area.
- Trusting construction drawings. Renovations are often not reflected in the drawings; a type B measurement shows the real situation.
- Basing square metres per employee on GFA. Rules of thumb for office space per person are usually based on NLA or on the number of workstations; see how many m² of office space you need per employee.
Frequently asked questions about GFA and NLA
What is the difference between GFA and NLA?
GFA is the total area measured along the outside of the building, including walls, shafts and stairwells. NLA is the part you can use as a tenant: the GFA minus construction, vertical circulation areas and plant rooms. For offices, the NLA is usually 80 to 90% of the GFA.
What does NLA mean?
NLA stands for net lettable area: the area under NEN 2580 on which the rent is usually calculated, including corridors and non-load-bearing walls, excluding stairwells, lifts and plant rooms.
How do you calculate GFA?
Measure the building's external dimensions per floor along the outside of the façade and add up all the floors. Spaces lower than 1.5 m and external areas such as balconies do not count.
Is a NEN 2580 measurement report mandatory?
Not by law, but in practice banks, valuers and professional tenants ask for it, and most ROZ lease agreements refer to it. Without a report, you're in a weak position in the event of a dispute over the area.
What is tare area?
The part of the GFA taken up by the construction: external walls, load-bearing internal walls, columns and shafts. Tare area is the difference between GFA and net floor area.
Not sure about the square metres in a listing? Our advisors check the measurement report and rental basis before you sign. Browse the current offices for rent or leave us your search brief.
