More than you'd think so what I do is take off the top piece of bread from the sub, always say no mayo, no salt, etc. maybe lil oil so it's not taotal dry, but it does sound yummy... what no black olives?
The roast beef foot long has 446 calories, so it's going to be somewhere around that. I don't think that includes the mayo so that's extra, plus I think you chose a different cheese than what's usually on it.