How can I tell how many bits my ssh key is?

[palvarez@oizon ~]$ ssh-keygen -l -f ~/.ssh/id_rsa.pub
2048 2e:8c:fd:aa:9f:95:86:9e:b0:d2:a6:1a:7e:d3:3e:74 .ssh/id_rsa.pub (RSA)

2048 bits.

Explanation:

  -l          Show the fingerprint of the key file.
  -f filename Filename of the key file.