かな・かしら: the difference
かなN4
Meaning
I wonder
Past papers
Example
もうすぐ食べに行くかな。
I wonder if we will go eat soon...
かしらN4
Meaning
I wonder
Past papers
Example
今日は雨が降るかしら。
I wonder if it will rain today.
How to tell them apart
「かな」: for everyone; the most natural for everyday self-talk.
「かしら」: traditionally used by women, with a soft tone: 「明日は雨かしら」.
「だろうか」: written or more formal self-questioning: 「これで十分だろうか」.