I am trying to compare the size of apartments that I see online with what I got over here in CA. Is there a standard that tells me what is included in the m2 figures in the ads? Are balconies a part of it, bathrooms, kitchen? Over here it seems the ads include even the toilet cover sqft as living space
Thanks.

There's the living space and the total space. In my house, the living space is everything except the boiler/laundry room and the nuclear bunker. The cellar is not included in the living space, unless it can be used as a living area. Balconies are not included.

There are so many ways to calculate m2 (with internal walls, wall-to-wall, with outer walls, balconies counted at 25%, surface where height in rooms is below 1.2 m counted as 50% etc), and also a general tendency to inflate the actual size when advertising, so the only thing I would rely on is looking at the place myself. With a measuring tape.

It is indeed confusing.

There are two measurements to caculate living space (Wohnfläche)The Brutto, which is what is calculated when a property is built, and this is what the architects use, then the Netto, which is the space taking into consideration the depth of the walls thereby resulting in the actual floor space. The difference between the brutto and netto can be 10-20%.

There are many creative people out there when it comes to ads but in theory what is to be counted are heated areas. However, many owners and agents tend to add unheated areas to the calculation if they deem the rooms can be used. This is less of an issue with an apartment. A balcony should not be counted.

A floor plan with room sizes is useful to have but many older apartments don't have the plan and the owners/agents can't be bothered to measure it. Some will use this service (it's mostly for properties for sale) so if you see one of these, don't panic. They are very accurate.
http://www.grundriss.com/index.php?lang=EN

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Thank you all for the input. Sounds not much different from here in CA then. Thought folks in CH are bit more honest when it comes to listing the size of an apartment they want to rent out. I have been gone for too long I guess.