Muscle Potential Calculator
How big can you getwithout drugs?
Your wrist and ankle already know the answer.
Wrist, ankle, height. Three numbers in, one honest number out: the most muscle your frame can carry without drugs. Most men train for years without ever knowing their true potential. See yours in a minute.
FFMI Calculator: Stop Guessing Your Muscular Potential.Calculate Your True FFMI
Pick your goal
Units and sex
Sex
Your body today
Height and target body fat are enough. Add your current weight and body fat to see exactly how much muscle you have left to build.
Get the tape out
Wrist and ankle don’t lie. They reveal your frame—and your frame defines your natural potential.
Current body measurements (Optional)
Grab a tape measure and enter your current numbers. We’ll show you exactly how close each muscle group is to its genetic potential.
Fill in the fields. Your numbers show up here. All in your browser, nothing saved.
Your natural potential, in black and white
Where you are. How far you can go.
- - You now
- - Your potential
Your maximum measurements, in lean shape
Every body part in detail
| Body part | You | Potential | % of Potential |
|---|---|---|---|
| Neck | |||
| Chest | |||
| Biceps | |||
| Forearm | |||
| Thigh | |||
| Calf |
Each percentage shows how close that muscle group is to its genetic potential for your frame. Status tags compare each area to your overall average so you know where to focus. Anything above 100% indicates elite genetics—or a measurement error (double-check your unit).
All measured relaxed, except biceps (flexed) and forearm (fist clenched), at ~8–10% body fat. This is a roadmap for balanced muscular symmetry, not a rigid rule. Hitting 95% of these numbers in lean condition will make you stand out in almost any gym.
The potential per body part was only ever published for men. Women get whole-body numbers.
This is the full potential of a natural lifter with top-tier genetics and years of flawless training. Built on data from elite natural bodybuilders, these targets run high for average genetics. Falling slightly short still yields a massive, head-turning physique. This is a scientific estimate, not a guaranteed promise or medical advice.
Your numbers
Where you stand
- 19 Average Untrained Man
- 22 Trained / Competitive Athletes
- 25 Upper end of natural potential
- 28 Largest documented natural trainee
For women, values are normalized to equivalent male reference points for accurate comparison.
A scientific estimate, not absolute proof. A 2% error in body fat shifts your FFMI significantly—ensure your inputs are precise.
Show them your numbers
One image. Your numbers, no excuses. The link lets everyone work out theirs.
Turn this number into a plan: book your free intake
Built on the published research of Dr. Casey Butt, considered as one of the most sophisticated formulas in the world of natural bodybuilding, based on true science to estimate your maximum lean body mass (LBM) at roughly 5% body fat. The maths runs in your browser. Nothing is stored.
Free guide
Know your number.Now build it.
The free 12-week guide shows you how: progressive overload, nutrition principles and tracking.
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How the numberswork
Most men train for years without ever knowing their true potential.
Your natural potential: the model looks at your height, your wrist and ankle size (the best simple read on your frame) and the body fat you want to be at. It estimates the heaviest lean physique a natural lifter with great genetics can reach. Most of us land a little below, and the number is less reliable if you are not lean.
Natty or not: the fat-free mass index (FFMI) tells you how much lean mass you carry for your height. In published studies, drug-tested natural athletes sit mostly below about 25. There are rare exceptions, so no number is proof, and a few points of error in your body-fat reading change the result.
Use it as a compass, not a verdict. What decides your result is simple: keep showing up and keep progressing with the right training, nutrition and recovery.