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Lean Body Mass Calculator

Calculate your lean body mass using the Boer formula based on gender, weight and height

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๐Ÿ‡ฉ๐Ÿ‡ฐ All calculations are based on Danish rules, rates, and currency (DKK). This calculator is translated for convenience but applies exclusively to Denmark.

Calculate your lean body mass

Lean body mass (LBM), also called fat-free mass, is your total body weight minus fat mass. It includes muscles, bones, organs, water and everything except body fat. Our calculator uses the Boer formula, a recognised method for estimating LBM based on gender, weight and height.

The Boer formula

The Boer formula calculates LBM as follows: Men: LBM = 0.407 x weight + 0.267 x height - 19.2. Women: LBM = 0.252 x weight + 0.473 x height - 48.3. The formula was developed by P. Boer and provides a quick estimate without body composition measurements.

Why is LBM important?

LBM is an important indicator of your health and fitness. A high LBM relative to total weight indicates a healthy body composition with relatively low body fat. LBM is also used to calculate your basal metabolic rate, as muscle tissue burns more calories at rest than fat tissue. LBM is also used for medication dosing and calculating protein needs.

How to increase your lean body mass

To increase your LBM, focus on strength training at least 2-3 times weekly, eating sufficient protein (1.6-2.2 g per kg body weight), ensuring caloric surplus when building muscle, and prioritising sleep and recovery. A gradual increase of 0.5-1 kg LBM per month is realistic for most people.

Frequently Asked Questions

What is the difference between lean body mass and muscle mass?

Lean body mass (LBM) includes everything except body fat โ€“ muscles, bones, organs, water, skin, blood etc. Muscle mass is only the skeletal muscle portion of LBM. Muscle mass typically accounts for about 40-50% of LBM in men and 30-40% in women. LBM is always higher than pure muscle mass.

How much lean body mass can you build?

According to research models, a man can build about 9-13 kg of muscle in his first training year, 4.5-6.5 kg in the second year, 2-3 kg in the third year, and under 1 kg in the fourth year and beyond. Women can typically build about half these amounts. The total muscle building potential over a lifetime is about 18-23 kg for men and 9-12 kg for women.

How is LBM used to calculate protein needs?

LBM can be used to calculate a more precise protein need than total weight, as it is muscle tissue (not fat) that needs protein. A recommendation is 2.2-3.3 g protein per kg LBM for strength training. For a person with 60 kg LBM, that equals 132-198 g protein daily. This method is especially useful for people with high body fat, as protein needs would otherwise be overestimated.

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