Daily Thai Confidence — Using แน่ใจ (nâe-jāi)

Verb: แน่ใจ (nâe-jāi)
Meaning: to be certain / to be sure (about something)

In this Thai lesson, we learn how to use the verb แน่ใจ (nâe-jāi), which means ‘to be certain’ or ‘to be sure’ about a fact or situation. It is often used for information, knowledge, or facts, rather than feelings of inner confidence. That is the role of the verb มั่นใจ (mân-jāi), which means ‘to be confident,’ ‘to be certain,’ or ‘to be sure’ about something. Just like the verb มั่นใจ (mân-jāi), แน่ใจ (nâe-jāi) must also be placed after the subject of the sentence (ประธานของประโยค — bprà-t^hāan k^hǎwng bprà-yôok).

The typical structure usually follow the pattern: subject + แน่ใจ (nâe-jāi) + complement (a clause or a prepositional phrase that completes the meaning of the verb).

For examples (ตัวอย่างเช่น — dtūa-^awyàang chên)

chǎn nâe-jāi wâa k^hǎo jà māa
Literal: I sure that he will come.
I’m sure that he will come.

The complement marker ว่า (wâa) means ‘that’ and is used to introduce the complement clause and to link the verb แน่ใจ (nâe-jāi = to be certain / to be sure) to the clause that completes its meaning.

t^hēr nâe-jāi wâa t^hēr bpìd bprà-dtōo lâew
Literal: She sure that she close door already.
She is certain that she had closed the door.

The complement marker ว่า (wâa) means ‘that’ and is used to introduce the complement clause and to link the verb แน่ใจ (nâe-jāi = to be certain / to be sure) to the clause that completes its meaning.

t^hēr nâe-jāi nāi k^hâw-mūun t^hêe t^hēr dâi māa
Literal: She sure in information that she receive come.
She is sure about the information she received.

The preposition ใน (nāi) means ‘in’ and is used to introduce the noun phrase ข้อมูลที่เธอได้มา (k^hâw-mūun t^hêe t^hēr dâi māa = the information (that/which) she received). Together, they form a prepositional phrase that completes the meaning of the verb แน่ใจ (nâe-jāi = to be certain / to be sure). Please note: The word ที่ (t^hêe = that / which) means ‘that’ or ‘which’ in this sentence and is used to introduce a relative clause เธอได้มา (t^hēr dâi māa = she received).

chǎn nâe-jāi wâa ród-fāi jà māa-t^hěung dtrōng wāy-lāa
Literal: I sure that train will come-arrive exactly on time.
I’m sure that the train will arrive on time.

The complement marker ว่า (wâa) means ‘that’ and is used to introduce the complement clause and to link the verb แน่ใจ (nâe-jāi = to be certain / to be sure) to the clause that completes its meaning.

Practise putting your newly learned Thai word into a sentence by translating the following sentences below.

1. He is sure about the answer he gave.
2. Are you sure that this address is correct?
3. I’m sure it will rain this afternoon.
4. She is sure about this information.
5. We’re sure this shop opens in the morning.

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Urai Khomkham

Hi, I’m Urai Khomkham, a Thai language teacher and the creator of Thai Language Tuition UK. I help learners understand how Thai really works, so they can stop guessing and start feeling confident using the language in real life. Inside the community, I share clear lessons, practical explanations, and gentle guidance to support steady, meaningful progress — without pressure or overwhelm. I also share free Thai lessons and learning tips on my YouTube channel, where I break things down step by step and help you build strong foundations at your own pace. By subscribing, you’re not only supporting your own learning — you’re also helping me continue creating free resources to support you and other learners on their Thai journey.

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