How long is an F1 race?
F1's Feature race is approximately 305 K's (190 M's) taking roughly an hour and a half but no more than 2 hours.
Monaco is an exception with respect to race length at 260 K's (161 M's) due to the, relatively, low speeds of the tight street circuit.
F1 also has a Sprint Race format, currently 3 events per season, that is approximately 100 K's (60 M's) and half an hour.