How to Say 'Mengetahui' in Casual Indonesian (Tau / Tahu)

Your textbook taught you mengetahui. It means "to know" or "to find out." Perfectly correct. Also.. almost never used in conversation.

The word you actually need is tau. Sometimes spelled tahu. Same word, same meaning. Just way more natural.

The Basics

Here's the gap between textbook and street:

• Formal: "Saya tidak mengetahui hal tersebut."
• Casual: "Gue gak tau."

Both mean "I don't know." One sounds like a government press release. The other sounds like a human being.

Tau works everywhere. With friends, at the warung, in texts. It's one of those words you'll hear dozens of times a day.

Phrases You'll Hear Constantly

Gak tau = Dunno. Probably the single most common casual phrase in Indonesian. Someone asks you something you don't know? Gak tau. That's it. Done.

Tau gak? = "You know what?" This one's a conversation opener. People drop it before sharing news, gossip, or something surprising. Tau gak? Dia udah pindah ke Bali. (You know what? He already moved to Bali.)

Kasih tau = Tell / inform. Literally "give knowledge." Super useful. Kasih tau gue dong! = Tell me! The dong adds that pleading, slightly pushy tone.

A Fun One: Tau-Tau

Tau-tau means "suddenly" or "out of nowhere." It has nothing to do with knowing things.. it's just how the language works.

Tau-tau dia udah pergi. Suddenly he was already gone.

You'll hear this a lot in storytelling. Something unexpected happened? Tau-tau...

One More Thing

Tahu also means tofu 🫠

Yeah. Same spelling, same pronunciation. Context makes it obvious though. Nobody's confused when you say gue gak tau .. they're not going to think you're anti-tofu.

Quick Recap

Formal	Casual	Meaning
mengetahui	tau / tahu	to know
tidak mengetahui	gak tau	don't know
memberitahu	kasih tau	to tell / inform
tiba-tiba	tau-tau	suddenly

Drop mengetahui from your active vocabulary. Keep it in your reading brain. Use tau for everything else.

So.. what other textbook words have you been using that nobody actually says? 🤔