Level 57

Total Experience Required 985,949

Level 100 progress: 14.44%

This is roughly the same as:

Killing 1,644 people in Warzone, or...
Killing 1,677 people in Execution, or...
Killing 1,393 people in Wingman, or...
Scoring 352,125 points in Guardian, or...
Scoring 1,071,684 points in Annex, or...
Scoring 648,651 points in Submission.

Horde (TU4)

Completing 2,465 waves on Casual, or...
Completing 1,644 waves on Normal, or...
Completing 1,233 waves on Hardcore, or...
Completing 986 waves on Insane.

Or a combination of the above. Have fun!