Level 41

Total Experience Required 326,650

Level 100 progress: 4.79%

This is roughly the same as:

Killing 1,089 people in Warzone, or...
Killing 1,112 people in Execution, or...
Killing 923 people in Wingman, or...
Scoring 233,322 points in Guardian, or...
Scoring 710,109 points in Annex, or...
Scoring 429,803 points in Submission.

Horde (TU4)

Completing 1,634 waves on Casual, or...
Completing 1,089 waves on Normal, or...
Completing 817 waves on Hardcore, or...
Completing 654 waves on Insane.

Or a combination of the above. Have fun!