Estimate muscle potential from wrist size, including flexed arm size, FFMI from height, weight and body fat, and classic body measurements.
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Muscle Potential Formula
The following rule-of-thumb formula is used in the Main tab to estimate flexed upper-arm size (as a simple “muscle potential” proxy) from wrist circumference. It is a proportional estimate, not a medical or scientific limit on natural muscle mass.
MP = WS \times 2.28
Variables:
- MP is the estimated flexed upper-arm circumference (inches)
- WS is the wrist circumference (inches)
In this calculator, the multiplier 2.28 is used as a classic proportion-based heuristic popularized in “classic physique” proportion charts. Coefficients can vary by source and may not generalize across sex, height, body type, or training status (the calculator converts from/to centimeters or millimeters as needed).
What is Muscle Potential?
On this page, “muscle potential” refers to a proportion-based estimate of what certain muscular measurements (such as flexed upper-arm size) might look like on a well-developed, relatively lean physique, using wrist (and sometimes ankle) circumference as a proxy for frame size. This is not a validated method for estimating an individual’s maximum achievable natural muscle mass or maximum lean body mass.
How to Calculate Muscle Potential?
The following steps outline how to estimate the Main-tab “Muscle Potential” (flexed upper-arm size) based on wrist size.
- First, measure your wrist circumference (WS) in inches (or enter it in cm/mm and let the calculator convert it).
- Next, use the formula MP = WS × 2.28.
- Finally, calculate your estimated flexed upper-arm circumference (MP) in inches (or convert to centimeters).
- After inserting your wrist size and calculating the result, check your answer with the calculator above.
Example Problem :
Use the following variables as an example problem to test your knowledge.
wrist size (WS) = 6.5 inches
Using the factor = 2.28
muscle potential (MP) = 6.5 × 2.28 = 14.82 inches
