Portuguese Phrase
Não tenho certeza.
Meaning
Literally, ‘I do not have certainty.’ In everyday speech it means ‘I’m not sure’ or ‘I’m uncertain.’ It conveys a polite, non‑committal stance.
When to use
Use this phrase when you want to express doubt about a fact, a plan, or someone’s request without sounding overly blunt. It works in both formal and informal contexts.
✦Grammar Breakdown
Nãotenhocerteza
Negação (Não)
‘Não’ precedes the verb to make the statement negative. It never changes form.
Verbo ‘ter’ (tenho)
‘Tenho’ is the first‑person singular present of ‘ter’ (to have). It is used here to mean ‘to have’ a state of certainty.
Substantivo ‘certeza’
‘Certeza’ is a feminine noun meaning ‘certainty’. It does not need an article after ‘ter’.
🗨In Conversation
Você vai ao cinema hoje à noite?
Are you going to the movies tonight?
Não tenho certeza. Ainda preciso confirmar o horário.
I’m not sure. I still need to confirm the time.
✕Common Mistakes
Não tem certeza.
The verb must agree with the speaker: use ‘tenho’ for ‘I’. ‘Não tem certeza’ means ‘he/she doesn’t have certainty.’
Não tenho certeza?
Adding a question mark turns the statement into a question, which changes the tone. Use a period for a simple statement of doubt.
Não tenho certeza de.
‘Certeza’ does not need a preposition after ‘ter.’ If you want to specify what you’re unsure about, use ‘sobre’ or ‘de’ with a noun phrase, e.g., ‘Não tenho certeza sobre o horário.’
↔Alternatives
Não sei ao certo.
I don’t know exactly.
Não estou certo.
I’m not certain.
Tenho dúvidas.
I have doubts.
Cultural Tip
In Brazilian Portuguese people often soften uncertainty with ‘não tenho certeza’ rather than a direct ‘não sei.’ It sounds more courteous and leaves room for clarification later. In formal settings (e.g., business meetings) you might add ‘no momento’ (at the moment) to stress that the uncertainty is temporary.