Window size ratio to room size - experiences?

Does this 10% rule also apply to the bathroom?

So, 1 sqm of window for 10 sqm of bathroom should probably be expected.
Tip: just look at apartments, drive around and look at windows and houses.
Or take a housing magazine. Pinterest makes it possible.

A bathroom is not a living space. Otherwise, by the way, many apartments would not be allowed to have an internal bathroom at all.

But if you build, you should be a bit generous, right?

Do you intend to exploit a lower limit, or why do you ask? - anyone who sizes windows reasonably for practical use will almost find it hard to accidentally fall below the minimum sizes.