The numbers you see below are how many shots it takes to kill an unarmored enemy by shooting them in the chest with no attachments at short range. Headshots deal exactly double damage (so if you need 5 bodyshots, you'll need 3 headshots). Hitting the arms or legs results in MUCH less damage, but it's also very inconsistent. By shooting the feet or hands you'll deal about half damage compared to the chest, but this gradually increases the higher you move up the limb.

In other words Head (2x) > Chest (1x) > Thigh > Shin > Foot (0.5x)

Fire modes, aiming down sights, crouching, going prone, etc. do NOT affect damage. But distance from your target does (the further the less)

Last updated for Patch 7

Melee damage can be quite inconsistent (I think headshots apply and if you spam attack it'll do less damage than if you wait between each hit) I simply tried a couple times and wrote down the least number of hits I needed to kill. So it's this or more: