accurate muscle measurement

I know it is often published how large someone's arms are...for example 17". Is this the true measurement of the actual muscle? My arms are 16.5 flexed but I have average sized biceps. The question is are my bicep muscles bigger than someone who has 14 inch arms? As I look through this site there seem to be plenty of photos that I would guess have bigger biceps than me. But I know their arms are less than 16.5 inches. So here is my thought and I guess question....... Would an accurate measurement of one's bicep be 1. Measure the bicep flex circumference 2. measure the wrist circumference. 3. Take BMI measurement of the bicep area.   Now subtract the wrist measurement from the bicep measurement. Subtract Bicep BMI from 100. Multiply x net bicep /wrist measurement???

Sorry I am not an engineer or mathematician so I am sure this could be better stated.....

Example:   17" bicep minus 10" inch wrist = 7"
100 minus Bicep BMI 25 would be .75
7 x .75 would be = 5.25 inch muscle which would indicate a more accurate size of the muscle...

Any thoughts?.....serious ones of course....... Any interest?

I don't believe BMI is important here. And I don't find important measuring only the bicep muscle. When you measure your biceps you are also measuring your tricep wich is not flexed and is completely relaxed. You would have to take many things in account to measure a muscle.