Ideal weight, small frame
Pick a small frame in the form to shift the range by 10 percent. The example is a man at 5 ft 8.5 in.
How it works
For males, Devine is 50 kg plus 2.3 kg per inch over 60. For females, it is 45.5 kg plus 2.3 kg per inch. Robinson and Miller use their own bases and steps. The page runs all three. For a man at 5 ft 8.5 in, 8.5 inches over 60 means the Robinson step adds 16.15 kg.
Worked example
Start with the height. 5 ft 8.5 in is 8.5 inches over 60. For a man, 50 + 2.3 × 8.5 = 69.55 kg is the Devine result. 52 + 1.9 × 8.5 = 68.15 kg is the Robinson result. 56.2 + 1.41 × 8.5 = 68.19 kg is the Miller result. Those are 153 lb, 150 lb and 150 lb. The range is 150 to 153 lb. A small frame moves the range 10 percent off: 150.25 × 0.9 = 135.225 and 153.33 × 0.9 = 137.997. The result is 135 to 138 lb.
Common questions
Why do the formulas give different answers?
Each uses its own base weight and its own amount per inch. The gap grows as height moves away from 5 feet. For a man at 5 ft 8.5 in the gap between the lowest and highest is 3 lb.
Do these formulas account for muscle or frame size?
No. They use only height and sex. Someone with a large frame or a lot of muscle can be healthy well above the range. For a man at 5 ft 8.5 in the range of 150 to 153 lb is a starting point, not a limit.
Is 150 to 153 lb a target I must hit?
No. It is a starting reference for a man at 5 ft 8.5 in. Your doctor can tell you what weight suits your own health. For a man at 5 ft 8.5 in the range spans 3 lb.
What if I am under 5 feet tall?
The formulas were written for heights of 5 feet and over. Below that the calculator uses the base weight. Treat the result as rough. For a man at 5 ft 8.5 in the formulas add 8.5 inches above the 60 inch base.
How does this compare with BMI?
A healthy BMI range also gives a weight range for your height. The two often overlap but they are not the same, because BMI ignores sex while these formulas use it. For a man at 5 ft 8.5 in a healthy BMI is 123 to 166 lb, against 150 to 153 lb here.