Many times I have asked students “How big is your home?” to which they reply, “No, no, no. My home is very small!”
Clearly they didn’t understand the question.
The same thing happens when I ask a simple question like “How tall is your husband?” The student will reply, “No, he’s very short!!!”
Yes, how + adjective can mean なんと・いかに . . . but it’s not that common, つまりその使い方はそんなに使われてない
Look at your dictionary and you will see that the first definition of “how” is どういう方法[手段]で, どのようにして, どんなふうに
▸ How did he get [find] the money?
彼はどのようにしてそのお金を手に入れた[見つけた]のか(!｟話｠ では時に強意的にHow on earth [｟ぞんざいに｠ the hell, ｟まれ｠ ever] did ...? (いったいどのようにして…したのか)のような形で用いる; → hell 1 語法 )
▸ “How did you go to school?” “I went by bike.” 「通学はどうしていたのですか」
「自転車で通っていました」
▸ “How does Ann drive?” “Very carefully.” 「アンの車の運転ぶりはどうですか」
「非常に慎重ですね」
The second definition of how is どのくらい, どれほど. And this is what is being asked by:
How . . . is it?
- big
- old
- tall
- long
- heavy
- far
For example:
▸ How old is your uncle? おじさんは何歳ですか
▸ How long will she be staying here? 彼女はいつまでここにいるのだろうか
▸ How far is it from Washington to New York? ワシントンからニューヨークまで(距離は)どれくらいありますか
▸ How soon does the movie begin? あとどのくらいで映画は始まるかな
▸ How many visitors are you expecting to come?お客さんは何人くらいの予定でしょうか
▸ How much money do you need? お金はいくら必要ですか
▸ I don't know how long the street is. その通りの長さはわかりません.
So, when you are asked:
How big is your apartment/home?
Don’t say:
✖️ No, it’s small!!!
Say:
⭕️ It’s a 3 LDK.
⭕️ It’s 80 square meters.
Or, when you are asked:
How tall is your husband?
Don’t say:
✖️ No, he’s very short!!!
⭕️ He’s about average height.
⭕️ He’s 170 cm tall.
⭕️ He’s quite short.
And, when you are asked:
How old is your baby?
Say:
He’s 6 months old.