"La domo havas du etaĝojn."

[bertilow]

The ground floor is also an "etaĝo". There are one-storey buildings. "unu-etaĝaj domoj".

[crlight]

Does etaĝo only refer to levels of a building or can it also refer to the ground of a building?

[Luis_Domingos]

"Floor" as in ground is "planko".

[errant1]

Think of "etaĝo" like "storey," as in "What storey is your room on?" In English, we also use the word "floor" interchangeably with "storey," but "planko" refers only to the physical surface of a building or domecile under one's feet.

[StephieRice]

It can, yes. That dependa on your locality.

Others have said theu locally hear "teretagxo" to mean "ground floor"

[Revilo_N]

Kiel oni kalkulas etaĝojn esperante, usona/japana/ĉinamaniere (ground floor = #1) aŭ eŭropa/afrika/aŭstraliamaniere (first floor above ground = #1)?

[jaggedSpire]

Ŝajnas al mi, ke la aŭskultanta ekzerco sonas kiel "tu" anstataŭ "du".