The formula for finding 1 RM on the bench press based on other things (like d-bell lifts, pushups, 40-yard dash time, how much money one earns, how many situps one can do in 60 seconds, how many women *or men if it's your cup of tea, no discrimination with the formula* one has slept with, etc etc) is very simple.
Get on a flat bench and find out.
Seriously, it just varies in every which direction with every person based on too many variables.