How do I calculate the living space correctly?

The basics: What counts as living space?

When you start calculating the living space , you first need to define which rooms qualify. According to common practice (based on the main usable area HNF according to SIA 416), this includes all areas that are used for living, are heated, and can be used year-round.

If you want to calculate the living space , you add the floor areas of:

• Living rooms and bedrooms.
• Kitchen and dining area.
• Bathrooms and separate toilets.
• Heated conservatories (provided they are insulated and habitable all year round).
• Corridors and hallways within the apartment.

A common mistake when laypeople calculate living space is including outdoor areas . In Switzerland, balconies, terraces, and loggias are not included in the net living space calculation. If you want to calculate the living space , you must list these areas separately as " outdoor space ." You cannot simply combine them with the interior spaces to artificially inflate the figure.

The problem with the sloping roof

Anyone who lives in an attic knows the problem: lots of charm, but little headroom. How can you fairly calculate the living space here ?

Here, Swiss practice often differs from German practice.

• Germany: Areas below 1 meter in height do not count at all, areas between 1 and 2 meters only count for half the area.
• Switzerland (SIA 416): If you want to calculate the living area strictly according to the standard , you measure everything that has a certain usability. However, in the practice of real estate valuation, the following rule of thumb has become established when calculating living area : Areas with a ceiling height of less than 1.50 meters are often not considered full living space, but rather "ancillary usable space" or storage space.

If you want to calculate the living space for an advertisement , it's fairest and safest to list areas with a height of less than 1.50 meters (knee wall) separately or omit them altogether. Trying to include the entire knee wall as living space will likely lead to disappointed faces during viewings and risk discussions about the rental price.

Basements and hobby rooms: living space or storage?

Another classic misunderstanding when owners calculate living space : the hobby room in the basement.

May I include these 20 square meters in the living space calculation ?

The answer depends on the features. To be able to calculate a basement room as living space , three conditions must be met:

• Heating: The room must have a permanently installed heating system.
• Light: Sufficient daylight must be available (windows, not just a light well).
• Ventilation: The indoor climate must be comfortable.

A damp basement storage room with a lightbulb counts as "ancillary usable area" (NNF). Including this in your living space calculation would be misleading. However, a finished basement room with a large window and radiator can be included in your living space calculation .

Net vs. Gross: The matter of walls

When architects calculate living space , they often refer to the "floor area". But for you as a resident, the "net living area" is what matters.

• Gross living area: Here you would calculate the living area by including the exterior walls. This is included in the measurement . This is relevant for building insurance, but not for the rent.
• Net living area: This is the area between the walls. If you want to calculate the living area for an advertisement , you measure from wall to wall (excluding baseboards ).

One detail often causes confusion when calculating living space : What about the interior walls? According to SIA 416, non-load-bearing interior walls are actually included in the net floor area. In common usage, however, living space is usually understood to mean the actual "carpeted area" (the floor space you can walk on). If you want to be on the safe side when calculating living space , specify in the listing whether it refers to the net living space (pure floor area). When calculating living space for mortgage purposes, banks often accept the net living space including the area of the interior walls (structural area), as these are considered part of the property's value.

Step-by-step instructions

So, how do you proceed practically when you want to calculate the living space ?

• a laser instead of a tape measure: Get yourself a laser measuring device. This will allow you to calculate the living space more precisely .
• Room by room: Measure the length times the width of each room. If you need to calculate the living area and the room is not rectangular, divide it into smaller areas (rectangles and triangles).
• Note deductions: When calculating the living area , deduct large pillars, chimneys or wall projections that reduce the floor space.
• Windows and niches: Window niches that don't reach the floor should not be included in the living area calculation . Floor-to-ceiling niches (door frames) are usually ignored or only included if they are very deep.

Why honesty lasts the longest

Why is it so important to calculate living space correctly ? Because the price per square meter is the number one metric for comparison . If you advertise a 100 m² apartment that actually only has 85 m² because you incorrectly included the balcony in the living space calculation , your price per square meter is artificially low. The tenant feels deceived.

Banks also use this figure to determine the market value. If you have the living space calculated incorrectly , the financing can fall through because the bank will adjust the value downwards. Therefore, calculating the living space correctly is not just a bureaucratic step, but the basis for trust and valuation.

Conclusion

In Switzerland, the question "How do I calculate living space correctly?" inevitably leads to the SIA 416 standard. Anyone who wants to calculate living space reliably focuses on the heated, habitable interior spaces (main usable area). Exterior areas such as balconies or unheated basements are not included in the calculation and must be listed separately.

Special care is required when calculating living space in rooms with sloping ceilings . Use the 1.5-meter line as a guideline to avoid disputes. Ultimately, accurately calculating the living space ensures transparency. An honest figure protects you from legal repercussions and allows for realistic price expectations. Take the time to have the living space professionally calculated or even measure it yourself with a laser measuring device – it's worth it.

If you are unsure how to calculate living space in complex floor plans or whether your hobby room officially qualifies as living space, Loft offers professional measurements and data analysis to correctly position your property on the market.

Glossary

• Standard SIA 416: The Swiss standard for calculating area in construction. It is the reference for professionally calculating living space .
• Main usable area (HNF): The term from SIA 416, which corresponds to what we mean in everyday life when we calculate the living area (living, sleeping, kitchen, bathroom).
• Net living area: The area between the exterior walls . Anyone wanting to calculate the living area uses this value to represent the effectively usable space.
• Outdoor area : Balconies, terraces and loggias. These must not be included in the heated living area ; they are listed separately.
• Knee wall: The height of the wall under a sloping roof. It is crucial when calculating the usable living space in the attic (often only relevant above a height of 1.50 m).