のって vs んだって

Both forms are common in casual speech, but they do different jobs.

Quick difference

• のって: gives an explanatory tone, like "you know..." or "the thing is..."
• んだって: reports what you heard, like "I heard that..."

When to use each

1) のって (explanatory)

Use it when the speaker is clarifying background or giving a reason in conversation.

• 今日は行けないのって、仕事が終わらないから。
  • "I can't go today, because work won't finish."

2) んだって (hearsay)

Use it when repeating information from someone else.

• 明日、休みなんだって。
  • "I heard tomorrow is a day off."

Common mistake

If your sentence means "I heard X," use んだって, not のって.