Muscle Calculator for Hard Gainers/Ectomorphs

0 Flares 0 Flares ×

This post comes as a response to the discussion following Michael’s post Muscular Potential and Reality“ at For a thorough background on the topic, go check out my original post Understanding Your Muscular Potential.

After I had built an Online Calculator which would predict a trainee’s maximum lean body mass, Michael ran his own stats on it and calculated his personal maximum lean body mass. Assuming Michael stays drug-free :), the calculator predicted he could add another 17 lbs of lean muscle mass to this frame.

He is skeptical. And rightly so. He has trained for years and adding 17 lbs of muscle is rather unrealistic. More importantly, he pointed out that the formula used for the online calculator didn’t include enough data points to make a precise prediction for all body types.

Based off Ellington Darden’s work, one of the additional data points that needs to be considered when predicting max lean body mass is the length of muscle bellies. The 3 guys in the image below have different body types. Their genetic potential of max lean body mass is largely determined by their bone structure and their muscle belly lengths.


If you want to know if you are a hard gainer with short muscle bellies, read what Casey Butt has to say on the topic:

„You can make a self-assessment of your muscle belly lengths by checking to see if you have longer tendons attaching your muscles to the bones than the average trainee of your height. In other words, do you have big gaps between the ends of your muscles and the bones to which they attach? If you do, then you have short muscle bellies in the muscles in question.“


If you have big gaps between the ends of your muscles, you are likely an ectomorph and will not achieve the max lean body mass that trainees with normal genetics can expect to achieve.

Upon Skyler Tanner‚s suggestion, I built an online calculator around the formula Casey Butt uses to predict max lean body mass in hard gainers/ectomorphs. This should be helpful to all those ectomorphs who are unwilling to accept their genetics and still dream about becoming a huge bodybuilding monster. I am sorry to say it: stop dreaming, and be realistic. Compared to the general public, as an ectomorph you will still be a beast if you train consistenly hard for long enough.


(Visited 4.835 times, 1 visits today)
0 Flares Facebook 0 Twitter 0 0 Flares ×
Speichere in deinen Favoriten diesen Permalink.
  • arcticTern

    Any ideas at all on how women should calculate their potential. Rapidly with regard to different body types?

    • Stephan R

      I really can’t give you a satisfying answer on this one. The muscular potential for females is going to be vastly different – just from a hormonal standpoint. But body type is still very relevant for women. Look at somebody like Serena Williams who has excellent genetics for example.

  • ProudDaddy

    Age makes no differenc?

    • Stephan R

      Absolutely it does. I would guess largely from a changed hormonal situation and a decreased work capacity and also longer recovery.

      If you start working out in your mid-30s or later, you definitely missed out on the hormonal sweet spot (age 19-26). I would guess the maximum lean mass potential may be acquired during a man’s age from 20-40.

  • SelfMadeUbermensch

    This is depressing. I’ve got pretty small wrists and ankles. According to this formula my maximum lean body mass is 196lbs which I’ve only come within a few pounds of once. I’m curious if anyone knows legit methods to build and thicken the tendons of the wrist and ankles? I know PRPM injections grow the tendons but thats out of my range financially. Got any DIY recommendations for tendon/ankle thickness?

  • Jason

    Unless I am entering the data wrong I have surpassed my bodies ability for Lean Muscle Mass.
    I am 6ft 3in tall, Ankle=9.5, Wrist=7.25, current body fat is 8.5%. Which puts me at max lean body weight of 187lbs. I currently weight 215lbs, with Body Fat of 8.5% that is only 18.27 lbs of body fat, which mean my lean body weight is 196.73lbs. Ive also been as heavy as 225 with 10%body fat, and I work in a sport that gets drug tested so I am drug free. How is that possible?

  • Alex

    I wanted to draw attention to The fact that the calculator specifically states maximum „Lean“ body mass.

    Correct me if I’m wrong, but is this referring Soli to muscle weight and not fat weight?

    For instance the Calculator said that my maximum lean body mass is 171 lbs. Am I then to add on 10% body fat weight for a maximum total body weight of 190 pounds? This seems like a reasonable weight.

    Let me know if I’m doing this right!