سایز این پیراهن برای من درست نیست.

A careful pronunciation is:

sāyz-e in pirāhan barāye man dorost nist

A more natural everyday pronunciation might sound like:

sāyz-e in pirāhan barām dorost nist

A few notes:

• سایز sounds very close to English size
• این = in
• پیراهن = pirāhan
• برای من often becomes برام in speech
• نیست is often pronounced nis in casual speech

So in conversation, you may hear something close to:

sāyz-e in pirāhan barām dorost nis

سایز means size, and it is a borrowed word, very likely from English through international usage. It is extremely common in modern Persian, especially in shopping and clothing contexts.

You will also see the more native Persian word اندازه, which also means size or measurement.

So both of these can work in similar contexts:

• سایز این پیراهن...
• اندازهٔ این پیراهن...

In everyday shopping Persian, سایز is very normal.

This is because of the ezafe construction, one of the most important features in Persian grammar.

In سایز این پیراهن, there is an unstressed -e sound after سایز:

• written: سایز این پیراهن
• pronounced: sāyz-e in pirāhan

That -e links size to this shirt, giving the meaning the size of this shirt.

In Persian writing, ezafe is often not written after words ending in a consonant, but it is still pronounced.

So:

• سایز این پیراهن = the size of this shirt
• pronounced as if it were سایزِ این پیراهن

Because این means this, and in Persian demonstratives normally come before the noun:

• این پیراهن = this shirt
• آن پیراهن = that shirt

This is similar to English word order.

So in the sentence:

• این پیراهن = this shirt
• سایزِ این پیراهن = the size of this shirt

برای من means for me.

It shows that the size is being judged in relation to the speaker. The idea is not just that the size is wrong in general, but that it is not right for me.

So:

• برای من = for me
• برام = colloquial spoken form of برای من

You cannot usually replace it with just من, because من by itself only means I / me, not for me.

In everyday speech, this sentence is often shortened to:

• سایز این پیراهن برام درست نیست

Yes, literally درست نیست means is not correct / is not right.

But in this sentence, it is being used more naturally to mean something like:

• isn't right for me
• isn't suitable for me
• doesn't work for me

In clothing context, English often says it doesn’t fit me right or it’s not my size, but Persian can use درست نیست more broadly to mean not right / not suitable.

So the sentence does not necessarily mean the shirt is grammatically or logically incorrect. It means the size is not appropriate for the speaker.

Because Persian uses forms of the verb to be differently from English.

Here:

• است = is
• نیست = is not

So نیست already includes the negative meaning.

The end of the sentence works like this:

• درست است = it is right
• درست نیست = it is not right

In casual speech:

• است is often dropped
• نیست is often pronounced shorter, like نیس

Because Persian usually follows Subject / Object / Verb order, and the main verb or copula typically comes at or near the end.

This sentence is structured like this:

• سایز این پیراهن = the size of this shirt
• برای من = for me
• درست نیست = is not right

So the whole pattern is:

[topic] + [for me] + [is not right]

That final position for نیست is very normal in Persian.

Yes. This sentence is understandable, but depending on the situation, some alternatives may sound more natural.

Common alternatives include:

• سایز این پیراهن برای من مناسب نیست.
  The size of this shirt isn’t suitable for me.

• این پیراهن اندازه‌ام نیست.
  This shirt isn’t my size.

• این پیراهن برای من تنگه.
  This shirt is tight on me.

• این پیراهن برای من گشاده.
  This shirt is loose on me.

So your sentence is fine, but in real shopping situations, many speakers might prefer مناسب نیست or اندازه‌ام نیست.

Because Persian does not use the the way English does.

Definiteness is often understood from context.

So:

• پیراهن can mean a shirt or the shirt
• سایز این پیراهن is understood as the size of this shirt

Since این already makes the noun specific, Persian does not need a separate word like English the.

Not always.

پیراهن can mean:

• shirt
• dress
• sometimes more generally a garment, depending on context

In modern everyday use, the exact meaning depends on what kind of clothing is being discussed.

In your sentence, if the given meaning is shirt, that works fine. But in other contexts, پیراهن might refer to a dress or another garment.

So learners should remember that پیراهن is a flexible clothing word, and context matters.