मैं अब थक गई हूँ।

Great question. In मैं अब थक गई हूँ, गई is not just part of to be. It adds the idea of becoming tired.

• थक गई हूँ = have become tired / am tired now
• It often sounds more natural than a plain literal I am tired

This pattern is very common in Hindi:

• बैठ गई हूँ = I have sat down / I’m seated
• भूल गई हूँ = I have forgotten
• सो गई हूँ = I have fallen asleep

So थक गई हूँ is not just a direct one-word equivalent of English am. It expresses a resulting state: I’ve gotten tired.

Because the speaker is understood to be female.

In Hindi, this part agrees with the gender of the speaker:

• मैं अब थक गई हूँ। = said by a female
• मैं अब thak गया हूँ। = said by a male

This is one of the first places English speakers notice gender agreement in Hindi. English does not change tired based on whether the speaker is male or female, but Hindi often does.

Sort of, but not exactly by itself in this sentence.

The basic verb is:

• थकना = to get tired / to become tired

In थक गई हूँ, थक is the verb stem/root part, and गई हूँ helps build the full expression.

So it is better to learn थकना as the dictionary form, rather than thinking of थक alone as a complete word meaning tired.

Related forms:

• थकना = to get tired
• थक गया / गई = got tired / became tired
• थका / थकी = tired

Yes. मैं थकी हूँ is also correct for a female speaker.

There is a small nuance:

• मैं थकी हूँ = I am tired
• मैं थक गई हूँ = I have gotten tired / I’m tired now

So थक गई हूँ often gives a stronger sense of a change of state, as in:

• I wasn’t tired before, but now I am.

That is why अब fits very naturally with it.

अब means now.

So:

• मैं थक गई हूँ। = I am tired / I’ve gotten tired.
• मैं अब थक गई हूँ। = I am tired now / I’ve gotten tired now.

It emphasizes that this is the speaker’s condition at this point.

Hindi word order is flexible, so you may also hear:

• अब मैं थक गई हूँ।

That means essentially the same thing.

हूँ is the first-person singular form of होना (to be) in the present tense.

It means am in sentences with I:

• मैं हूँ = I am

In this sentence, it completes the expression:

• थक गई हूँ

Without हूँ, थक गई can still appear in conversation, but थक गई हूँ is the full standard form.

Compare:

• मैं थक गई। = I got tired. / I became tired.
• मैं थक गई हूँ। = I have gotten tired / I am tired now.

It is usually pronounced roughly like guh-EE or gai/ga-ee, depending on accent and speed.

A simple learner-friendly transliteration is:

• main ab thak gaī hū̃

A few pronunciation notes:

• मैं sounds like main but nasalized
• थ is an aspirated t sound, not an English th as in think
• गई has two vowel sounds: ga-ī
• हूँ is hoon with nasalization

In everyday speech, many speakers say something close to gayi.

Because मैं simply means I, and it does not change for gender.

The gender shows up elsewhere, especially in words like:

• गया / गई
• थका / थकी

So Hindi often marks gender on verbs, participles, or adjectives, not on the pronoun I itself.

It is neutral and completely natural in everyday Hindi.

It works in many situations:

• casual conversation
• speaking to family or friends
• ordinary polite speech

Nothing in this sentence is especially slangy or especially formal.

If you want the male version, it is equally natural:

• मैं अब थक गया हूँ।

Yes. Hindi word order is more flexible than English word order.

These are all natural:

• मैं अब थक गई हूँ।
• अब मैं थक गई हूँ।

The first one is a very straightforward neutral order.
The second may place a little more emphasis on now.

Even with flexible word order, the verb phrase usually stays toward the end.

It can overlap with both, depending on context.

Most often in everyday use:

• मैं थक गई हूँ = I am tired
• but with a sense of I have become tired

So if someone has been working, walking, or studying for a long time, this sentence naturally means:

• I’m tired now
• I’ve gotten tired

If you want a more simple adjectival idea, मैं थकी हूँ also works, but मैं थक गई हूँ is extremely common and natural.

The male version is:

• मैं अब थक गया हूँ।

Only one word changes:

• गई → गया

Everything else stays the same.

So:

• female speaker: मैं अब थक गई हूँ।
• male speaker: मैं अब थक गया हूँ।

Yes, very naturally.

That is one of the most common uses. For example, after:

• working a long day
• walking a lot
• studying for hours
• cleaning the house
• traveling

you can say:

• मैं अब थक गई हूँ।

It sounds very normal for ordinary, temporary tiredness.