Lean body mass by height and weight
Estimated lean body mass in pounds by the Boer formula. Find your weight in the first column and read across to your height.
Men
| Weight | 5′4″ | 5′7″ | 5′10″ | 6′1″ | 6′4″ |
|---|---|---|---|---|---|
| 120 lb | 102 | 107 | |||
| 140 lb | 110 | 115 | 119 | ||
| 160 lb | 118 | 123 | 127 | 132 | 136 |
| 180 lb | 127 | 131 | 136 | 140 | 145 |
| 200 lb | 135 | 139 | 144 | 148 | 153 |
| 220 lb | 143 | 147 | 152 | 156 | 161 |
| 240 lb | 151 | 156 | 160 | 164 | 169 |
| 260 lb | 159 | 164 | 168 | 173 | 177 |
| 280 lb | 167 | 172 | 176 | 181 | 185 |
Women
| Weight | 5′0″ | 5′3″ | 5′6″ | 5′9″ | 6′0″ |
|---|---|---|---|---|---|
| 100 lb | 78 | ||||
| 120 lb | 83 | 91 | 99 | ||
| 140 lb | 88 | 96 | 104 | 112 | 120 |
| 160 lb | 93 | 101 | 109 | 117 | 125 |
| 180 lb | 98 | 106 | 114 | 122 | 130 |
| 200 lb | 103 | 111 | 119 | 127 | 135 |
| 220 lb | 108 | 116 | 124 | 132 | 140 |
| 240 lb | 113 | 121 | 129 | 137 | 145 |
A formula from height and weight gives everyone of the same size the same figure. If you have a body fat measurement, the calculator above uses it instead. Cells are blank where the height and weight give a body mass index under 18.5: the formula is a straight line, and toward that corner it runs away. For a woman of 5 ft 9 in and 100 lb it returns 101 lb of lean mass, more than her body weight.
How it works
Lean body mass is body weight minus fat. If you know your body fat percentage, the sum is direct: weight × (1 − body fat ÷ 100). The answer is only as good as the body fat figure.
Without a body fat figure, lean body mass can be estimated from height, weight and sex. The three formulas here come from clinical research, where lean body mass is used to scale things such as body fluid volumes and drug doses.
- Boer (1984) used lean body mass estimated from height and weight to compare blood volume and extracellular fluid volume between people, in a study of 66 healthy subjects.
- James (1976) comes from a UK report on obesity research. It subtracts a term in weight squared, so above a body mass index of 43.0 for men and 36.1 for women it gives less lean mass as weight goes up. The calculator leaves it out above that point.
- Hume (1966) fitted lean body mass, calculated from total body water, to height and weight in 29 men and 27 women aged 37 to 80: people with no apparent disorder and patients with chronic bronchitis, polycythaemia vera or obesity.
The calculator shows all three. Boer’s leads because the James formula breaks down at high body mass index and Hume’s was built on 56 people. When you enter a body fat percentage, the figure from it leads instead.
The formula
From body fat
lean = weight × (1 − fat ÷ 100)
From height and weight
W = weight in kg
H = height in cm
Boer
men = 0.407 W + 0.267 H − 19.2
women = 0.252 W + 0.473 H − 48.3
James
men = 1.10 W − 128 × (W ÷ H)²
women = 1.07 W − 148 × (W ÷ H)²
Hume
men = 0.32810 W + 0.33929 H
− 29.5336
women = 0.29569 W + 0.41813 H
− 43.2933
kg = lb ÷ 2.20462
cm = inches × 2.54Worked example
A man who weighs 180 lb and is 5 ft 11 in tall.
- Weight: 180 ÷ 2.20462 = 81.65 kg. Height: 71 inches × 2.54 = 180.34 cm.
- Boer: 0.407 × 81.65 + 0.267 × 180.34 − 19.2 = 62.2 kg, which is 137.1 lb.
- James: 1.10 × 81.65 − 128 × (81.65 ÷ 180.34)² = 63.6 kg, which is 140.2 lb.
- Hume: 0.32810 × 81.65 + 0.33929 × 180.34 − 29.5336 = 58.4 kg, which is 128.8 lb.
- The three differ by 5.1 kg (11.3 lb).
If the same man knows his body fat is 15%, the direct figure is 180 × (1 − 0.15) = 153.0 lb.
Why the James formula is left out at high BMI
The James formula takes away a term that grows with the square of weight. For a given height, lean mass by this formula rises with weight, reaches a peak, and then falls. A 2014 paper in the Journal of Nuclear Medicine puts the peak at a body mass index of about 43 for men and 37 for women. The algebra gives 43.0 and 36.1.
For a man of 5 ft 10 in, the formula gives 165 lb of lean mass at 300 lb, 162 lb of lean mass at 340 lb and 153 lb of lean mass at 380 lb. The same paper reports that the James formula breaks down at very high body weights, so past the peak the calculator shows the Boer and Hume figures only.
Limits of the estimates
- Height and weight cannot separate muscle from fat. A lean, muscular person and a person with more body fat get the same estimate if they are the same height and weight, although their lean mass differs.
- The formulas come apart at the extremes of size. A 2005 paper on predicting lean bodyweight describes the existing methods as inconsistent there. The Boer and Hume formulas are straight lines, so at a low weight for a height they put a larger and larger share of body weight as lean mass: for a woman of 5 ft 9 in and 100 lb, Boer returns 101 lb. The calculator adds a caution below a body mass index of 18.5 and does not show a figure that exceeds body weight.
- Hume reported the scatter around his own formula: a standard deviation of 2.3 kg for men and 5.4 kg for women. He wrote that the figure for women may be a little large for predicting one individual.
- Hume’s subjects were 56 people aged 37 to 80, some of them hospital patients. Boer’s were 66 healthy subjects in a study of body fluid volumes. This page cannot say how well any of the three formulas fits people who lift weights.
- From a body fat percentage the arithmetic is exact, and the error is whatever error the body fat figure has.
Questions
How do I calculate lean body mass?
If you know your body fat percentage, multiply your weight by one minus body fat as a fraction. At 180 lb and 15% body fat that is 180 × 0.85 = 153.0 lb. Without a body fat figure, a formula from height and weight gives an estimate: the Boer formula gives 137.1 lb for a man of 180 lb, 5 ft 11 in.
What is the Boer formula for lean body mass?
For men, lean body mass in kg = 0.407 × weight in kg + 0.267 × height in cm − 19.2. For women it is 0.252 × weight + 0.473 × height − 48.3. Convert pounds to kilograms and inches to centimeters first. The James and Hume formulas are in the formula section above.
Which lean body mass formula is the most accurate?
None of them measures you, and they were built on different people for different purposes. For a man of 180 lb, 5 ft 11 in they give 137.1 lb (Boer), 140.2 lb (James) and 128.8 lb (Hume). The James formula is known to break down at high body mass index. If you have a body fat measurement, the figure from it describes you better than any of the three.
Is lean body mass the same as muscle mass?
No. Lean body mass is everything in the body that is not fat, which includes bone, organs and body water as well as muscle. Hume, for example, calculated it from measurements of total body water.
Is lean body mass the same as fat-free mass?
Close enough that the terms are often used for each other. A 2005 paper on predicting lean bodyweight says fat-free mass is considered to closely approximate it. The FFMI calculator uses the same weight × (1 − body fat) sum and calls the result fat-free mass.
Why does the calculator need my sex?
Each of the three formulas has one version for men and one for women, with different numbers, because the studies fitted them separately. The direct sum from body fat percentage is the same for everyone.
Add this calculator to your site
Gym, coach or blog? You can put this calculator on your own site for free. Copy the code below into your page’s HTML. The calculator updates itself whenever we improve it.
The short script lets the frame grow to fit the calculator on your page. Please keep the credit line underneath it.
Sources
- Boer P. Estimated lean body mass as an index for normalization of body fluid volumes in humans. American Journal of Physiology. 1984;247(4 Pt 2):F632-F636. The equations are quoted from the two papers that follow.
- Caruso D, De Santis D, Rivosecchi F, et al. Lean body weight-tailored iodinated contrast injection in obese patient: Boer versus James formula. BioMed Research International. 2018;2018:8521893. Equations 1 to 4.
- Henning MK, Gunn C, Arenas-Jiménez J, Johansen S. Strategies for calculating contrast media dose for chest CT. European Radiology Experimental. 2023;7(1):29. Table 1.
- James WPT, Waterlow JC. Research on Obesity: a report of the DHSS/MRC group. London: Her Majesty’s Stationery Office; 1976. The equations are quoted from Tahari et al. and the two papers above.
- Tahari AK, Chien D, Azadi JR, Wahl RL. Optimum lean body formulation for correction of standardized uptake value in PET imaging. Journal of Nuclear Medicine. 2014;55(9):1481-1484. Equation 2 and the point where the James formula turns down.
- Hume R. Prediction of lean body mass from height and weight. Journal of Clinical Pathology. 1966;19(4):389-391.
- Janmahasatian S, Duffull SB, Ash S, Ward LC, Byrne NM, Green B. Quantification of lean bodyweight. Clinical Pharmacokinetics. 2005;44(10):1051-1065.
- National Institute of Standards and Technology. Guide for the Use of the International System of Units (SI), Special Publication 811, Appendix B.9: 1 inch = 2.54 cm and 1 lb = 0.4535924 kg.