750 or up will take it down in one shot, but I have taken one down with a 450 fps but I had to shoot it a couple times. it mostly depends on shot placement. A good choice would be a chrossman 760, daisy powerline 880, or just about game pellet rifle.
It's all in the caliber and fps.
phosphor, paintball paradise, and orange fps
pound-force per feet2 (lbf/ft2)
If you want an answer then you need to specify a particular model. Depending on the model the FPS can be anywhere between 300 FPS to over 1600 FPS.
PSI is a pressure measurement. FPS is a speed measurement. It's not possible to convert between the two without a great deal of additional information (it might, for example, be possible to convert a pressure measurement in the chamber of a gun to an expected muzzle velocity of the projectile, with sufficient additional information).
5675765765576576 fps or 66687768867jghhj fps
120 fps 90 fps 60 fps
600 FPS - Pellet 625 FPS - BB
.12 gram bbs.
350FPS would be sufficient
Normally a 600-700 fps air rifle will kill a rabbit at around 30-40 yards away. So this will include a .22 caliber air rifle or if your looking for something with less power that will just kill birds, try looking for a .177 or .20 caliber air rifle but if you are looking to hunt game like rabbits go for .22
450 FPS BB 400 FPS Pellets