Field of View FoV, use your fist it's 10degrees wide, Full Frame!

To get an idea of how much is a "numerical" FoV say 30degrees?
Clinch your hand into a fist, and keep it stretched away from the eyes, n what your fist covers Horizontally is about 10degrees.

Non-Full Framer should use the (Multiplier 1.6) effective Focal Length.