Muscle Gain Calculator

How It Works

Muscle gain slows dramatically with training experience — this is sometimes called the "Law of Diminishing Returns." A male beginner can gain about 9-11 kg of muscle in the first year of proper training. In year two, that drops to about 4.5-5.5 kg. By year three and beyond, gains slow to 1-2.5 kg per year. These estimates are based on the Lyle McDonald and Alan Aragon models. Women can gain roughly half the muscle of men due to lower testosterone levels. Age over 40 slows gains by about 20%, and higher body fat levels slightly impair muscle building due to hormonal changes. During a bulk, some fat gain is inevitable — the best lean bulks achieve a 2:1 or 3:1 muscle-to-fat ratio. Keep your surplus moderate (200-400 calories) and prioritize protein at 2.0 g/kg body weight.