A pint of your average 5% beer/lager has around 170 kCal. Your daily recommended intake of calories, as an active adult male is around 2,500 kCal. so 6 pints of beer daily = 900kCal a day, close to half your recommended daily maintenance intake of 2,500 kCal.
If you really wish to monitor your calorific intake over concerns about putting on weight, keep a calorie record. Be honest and record everything you eat and drink during the day, then look up what that amounts to. You will be surprised. It is astonishing how easily people "forget" snacks, bars of chocolate, bags of crisps, Kebabs and all sorts, when totting up what they have consumed during the day. People lie about this kind of thing :) Lie to themselves, lie to others.
And more generally - you can , of course, drink whatever you want -you are, as an adult, entitled to drink whatever you want - but 5/6 pints a day? Not good for your health over the long term.