The AKC states the normal Bullmastiff should be 110-130lbs full grown. However there isn't a standard to compare year-old dogs against, if your Bully appears to be healthy and active chances are he's normal weight. There are going to be males who are only 75 lbs at a year and some like ours who was 135lbs at a year (both can be considered ideal based on lineage). Typically they will continue to grow even beyond two years, at a year he should be showing max height but will continue to bulk up with muscle. Happy feeding!!