Theres no ideal proportion here or ideal male thigh size but the goal should be athletic legs with solid muscle size and explosive strength. Its difficult to calculate lean body mass let alone muscle mass.

Understanding Your Measurements Tanita Corporation
Body muscle measurement chart. Measure both right and left sides of the body. For bodybuilders the waist and hip measurements from chart 1 are a better off season guide. They are still useful. Your diet also plays a role in building muscle. The natural way steve reeves outlined his formula for the ideal body proportions as follows muscle to bone ratios. Everyone is built differently with their own unique fat distribution.
The ideal male body doesnt have massive tree trunk legs nor does it have skinny chicken legs. Yes having a low body fat percentage means you are keeping your body in tip top condition and brings several health benefits which can be very beneficial and yes having a healthy bmi is important in making sure that you do not become over or underweight but many people forget about their muscle mass percentage which is what it sounds like the percentage of your body mass that is muscle. A better gauge of waist and hip girth in bodybuilders is body fat level. Increasing your protein intake is important because protein helps. Muscle mass is a part of your lean body mass. The body measurement chart would probably show a difference though since muscle takes up less room in the body.
As a matter of general health body fat levels as high as 20 are acceptable provided good cardiovascular condition is demonstrable. Muscle mass muscle mass is the percentage of muscle in the body as compared to total body weight. In his book building the classic physique. Pull the tape tight keeping pressure against but not pinching the skin and ensure the tape is kept level and not. The cells join together increasing the size and strength of your muscle fibers. Keep the feet together relax your muscles and stand up straight.
For example a 42 year old man with 24 body fat is considered to have average body fat percentage. The most accurate methods are expensive and there isnt a lot of reliable data. It is important to remember that any body fat chart show averages only. Having these 3 body parts all measure the same was one of his criteria for ideal body proportions. People arent jumping up behind you seeing that scale creep up but they may notice if you gain or lose inches. Plus inches are what people see.
To accurate assess symmetry. If one muscle group is out by however much it will need to be prioritized. Generally take measurements in an unflexed state and before your workout not after. Meaning the balance between body parts both sides of the body need to be measured. Consistency is essential measure under the same conditions and using the same equipment each time. Arm size 252 of wrist size calf size 192 of ankle size.
How to get well developed but proportional legs.