The guideline for general health is .5-.8g per KILOGRAM of bodyweight... for building mass, it ranges between 1.0-1.5g per KILOGRAM. However, I personally need a heck of a lot more than this. I go by pounds instead of kilograms. I basically just try to get as much as I can per day (because it's hard for me to get too
much). If I get over 20% of my kcals from protein, then I'm happy. I try to get at least 120g at the very least. I think it just depends on your goals and your body. If you are trying to put on mass, you will obivously be eating more, thus you will be inadvertingly getting more protein than the average person. Some people work best on higher amount of protein, and some people excel at lesser amounts. I need a lot in order to feel/be healthy and maintain/gain muscle. But, thats just me.