よ details
write + I'm telling you — marks the finished sentence as news for the listener
kaku yo
I'm telling you — marks the finished sentence as news for the listener
その電車、もう出ましたよ。
sono densha, mou demashita yo.
That train's already left, you know. neutral
早く行こうよ、間に合わないよ。
hayaku ikou yo, ma ni awanai yo.
Come on, let's go — we won't make it. casual
- dictionary form
- past
- negative
- negative + past
- polite
- polite + past
- polite + negative
- polite + negative + past
- noun
- volitional
Examples
telling — the speaker supplies something the listener does not know yet
その電車、もう出ましたよ。
sono densha, mou demashita yo.
That train's already left, you know. neutral
鍵、テーブルの上に置いたよ。
kagi, teeburu no ue ni oita yo.
I put the keys on the table. casual
pressing — the same push behind an invitation, a warning or a request
早く行こうよ、間に合わないよ。
hayaku ikou yo, ma ni awanai yo.
Come on, let's go — we won't make it. casual
あまり無理しないでくださいよ。
amari muri shinaide kudasai yo.
Please don't push yourself too hard. neutral
Formation
{S}よattaches to finished clause{N}だよattaches to noun{V-volitional}よattaches to volitional
Notes
downward freely and stays rare upward — 承知しましたよ reads as
impatience, not politeness.
Related patterns
Similar
Both deliver something the listener does not have, but よ simply hands over the fact (電車、遅れてますよ), while んです frames it as the account behind something already in view (遅れたんです explains the lateness someone has just noticed).
The pair that splits by who holds the information — ね hands the sentence over for agreement about something both already see (暑いですね), よ hands over the information itself (もう出ましたよ); ね on a third-party fact the listener cannot know is odd (×田中さん、結婚しましたね), よ on the weather you are both standing in is pushy.