いくつになったの?
How old are you now?
How old have you turned?
[お誕生日おめでとうございます。](https://eikaiwa.dmm.com/uknow/questions/51925/)
Wish you a very happy birthday.
Many happy returns of the day.
[遅ればせながら](https://eikaiwa.dmm.com/uknow/questions/16910/)誕生日おめでとうございます。
Belated happy birthday.
Happy belated birthday.
ご参考になれば幸いです。
Happy birthday! May I ask what age you are celebrating?
Yes, the topic of discussing someone's age may be a delicate one depending on the person involved. It is probably a decision you will have to make yourself. However, in general, it is considered impolite in the UK to ask a mature woman her age - unless that is a specific topic in a conversation, or unless you know this person quite well. Men are usually less sensitive about their age and more willing to discuss it, but it is a personal detail and may be taken as an intrusion into personal privacy.
"Happy birthday! May I ask what age you are celebrating?"
"I never discuss my age, sorry."
>Happy birthday, how old are you now if I may ask?
*This is asking in a polite way how old he/she is now.
>Happy birthday, What is the lucky number?
*This is an informal way of asking. "Lucky number" is referring to the "new age".
Happy birthday, how old are you now if I may ask?
今、相手が何歳かを丁寧に尋ねる方法です。
Happy birthday, What is the lucky number?
フォーマルではない聞き方です。「Lucky number」とは「new age（新しい年）」を意味します。
Instead of saying"Anyway how old are you going to be?" you can say "Anyway how old are you now?"
You can use the following sentences to express yourself:
Happy birthday. How old are you now?
If you don't mind me asking how old are you now?
"Anyway how old are you going to be?"と言う代わりに "Anyway how old are you now?"と言う事が出来ます。
次の表現を使って言い表すことが出来ます。
Happy birthday. How old are you now?
お誕生日おめでとう。何歳になったの？
If you don't mind me asking how old are you now?
何歳になったか聞いてもいい？
Both polite questions as it is a very awkward question to ask. More informal almost slang with a friend could be something as simple as how many candles are you burning(birthday cakes have candles).
どちらも丁寧な言い方です、とても気まずい質問ですからね。
もっとカジュアルで、スラングに近い言い方ですが：
How many candles are you burning?
〔訳〕ろうそく何本立てるの？（バースデーケーキにはろうそくが立っていますね）
It was his birthday, but he wouldn't say how many "miles were on the clock!"
An amusing way to ask "how old some one might be"...(as used for cars)
How many "miles are on the clock!" some people " hate to discuss their age".
and it can be sensitive subject as we get older...Especially among ladies!
"how old some one might be"（ある人が何歳なのか）を聞く面白い聞き方のひとつとして、次のようなものがあります。
"How many miles are on the clock!"（（車のことを尋ねるように)何マイルと計測されていますか？）
" hate to discuss their age".（年齢について話すことを嫌う）人もいます。
年をとればとる程、特に女性の間では、注意した方が良い話題です。
"Happy birthday," is the term we use to wish this special day to someone. We can ask, "how old are you," or, "how old are you going to be," to simply ask what their age is now and it would not come off as rude as it is a common question at a birthday. We can also use the verb, "to turn," to express that we are going from one age to the next.
インド 
イギリス 
日本 
南アフリカ 
アメリカ合衆国 
