At a loose end:

British English If you're at a loose end, you have nothing to do.

If I'm ever at a loose end, I look for a good book to read.

Give me a call if you're at a loose end and we'll go and do something.

Persian:
بی کار بودن

Note: This is similar to the American idiom "at loose ends", though the American idiom seems to indicate a state of unhappy restlessness that results from having nothing to do, while the British idiom simply means having nothing to do.

Persian:
کلافه بودن