My current stats are inaccurate since I was a lot worse at this game when I first started compared to how I am now. So, I've been manually calculating the stats based on my current averages. Based on my session stats, I get an average of 30,000 score per hour currently. I took 30,000 and divided it by 60, which gave me 500 score per minute. Did I calculate that right? My stats page says I have 185.8 score per minute, which is a pretty big difference from 500, so I'm not sure if that's correct.
It calculates on total playtime. So if you dick around in the warpgate or go afk to take a dump, that will count against you.
Since that takes into count your noob days, it's going to be lower than what you currently are. But yes SPH/60 = SPM EDIT: it might even take in your total score / time in game not just individual "sessions".