Kaç yaşındasın?

A useful rough breakdown is:

• kaç = how many
• yaş = age / year of age
• yaşında = at the age of / years old
• -sın = you are for you singular, informal

So the whole sentence means How old are you?
Literally, it is closer to How many years old are you?

Because Turkish is an agglutinative language: it often builds meaning by attaching endings to a base word instead of using separate words.

Here, yaşında is the age expression, and -sın is the ending meaning you are. English uses separate words, but Turkish often joins them together, so yaşındasın is one word.

In Turkish, the idea of to be is often expressed with an ending rather than a separate verb.

So in Kaç yaşındasın?, the -sın at the end already means you are. That is why Turkish does not need a separate word like English are here.

A simple approximation is:

kach yah-shun-DA-sun?

A few sound notes:

• ç sounds like ch in chair
• ş sounds like sh in shoe
• ı is a Turkish vowel that does not exist in English; it sounds a bit like a short, relaxed uh, but farther back in the mouth

So yaşındasın is not yashindasin with a normal English i sound. The ı is different.

Because of vowel harmony.

Turkish suffixes often change their vowel to match the vowels earlier in the word. One common set is:

• -sın
• -sin
• -sun
• -sün

Which one you use depends on the previous vowel. In yaşındasın, the vowel pattern requires -sın.

This is a very common feature in Turkish, so you will see it everywhere.

No. You usually do not need to say sen.

Kaç yaşındasın? already means How old are you? because -sın tells you that the subject is you singular.

You can say Sen kaç yaşındasın?, but that adds emphasis, contrast, or emotional force. In normal conversation, Kaç yaşındasın? is enough.

Use:

Kaç yaşındasınız?

The ending -sınız is the polite or plural form of you are.

So:

• Kaç yaşındasın? = informal singular
• Kaç yaşındasınız? = polite singular or plural

You would use Kaç yaşındasınız? with someone older, someone you do not know well, or when speaking more formally.

Yes. A very common alternative is:

Yaşın kaç?

This also means How old are you?

It is built differently, more like Your age is how many?, but in natural English the translation is still How old are you?

Both are common:

• Kaç yaşındasın?
• Yaşın kaç?

The formal version of the second one is:

Yaşınız kaç?

You answer with a number plus yaşındayım if you are talking about yourself.

For example:

• On yaşındayım. = I am ten years old.
• Yirmi yaşındayım. = I am twenty years old.
• Otuz beş yaşındayım. = I am thirty-five years old.

You can also add ben, but it is usually unnecessary:

• Ben yirmi yaşındayım.

Because the ending changes with the person.

• yaşındayım = I am
• yaşındasın = you are singular, informal
• yaşındasınız = you are polite/plural

The -y- in yaşındayım is a buffer consonant. Turkish often inserts y when a suffix is added after a vowel, so the word is easier to pronounce.

It can be used for both children and adults. Grammatically, it works for any age.

However, just like in English, asking someone’s age can sometimes feel personal depending on the situation. So the grammar is completely normal, but the social appropriateness depends on context. With strangers or older people, the polite form Kaç yaşındasınız? is safer.

Not perfectly.

A word-for-word approach can help you understand the structure, but the natural English translation is simply How old are you?

Trying to match every Turkish piece to an English word can be useful for study, but it is better to remember that Turkish expresses age differently from English. Turkish uses an age expression plus a to be ending, while English uses old.