Quick answer
The Boer formulas estimate lean body mass: men 0.407 × weight (kg) + 0.267 × height (cm) − 19.2; women 0.252 × weight + 0.473 × height − 48.3. A 70 kg, 175 cm man has 56 kg of lean mass and 14 kg of fat mass.
Enter units, sex, weight and height. The calculator returns lean body mass and body fat mass.
Related tools: FFMI Calculator: Fat-free mass index and its height-normalized value. Center of Mass Calculator: Center of mass of point masses in one or two dimensions. Molar Mass Calculator: Molar mass and mass percent composition of a chemical formula.
How to use the Lean Body Mass Calculator
- Choose units: Metric (kg, cm) and Imperial (lb, in).
- Choose sex: Male and Female.
- Enter weight (kg, or lb) (between 20 and 500).
- Enter height (cm, or in) (between 100 and 250).
- Press Calculate to see the result, and use Reset to start again.
| Input | What to enter | Allowed values |
|---|---|---|
| Units | Choose one: Metric (kg, cm); Imperial (lb, in) | Starts at Metric (kg, cm) |
| Sex | Choose one: Male; Female | Starts at Male |
| Weight (kg, or lb) | A number | ≥ 20, ≤ 500 |
| Height (cm, or in) | A number | ≥ 100, ≤ 250 |
Formula and method
Formula
Men: LBM = 0.407w + 0.267h − 19.2; Women: LBM = 0.252w + 0.473h − 48.3 (w in kg, h in cm)
IEEE-754 double precision; shown to 1 decimal place unless stated.
Boer's equation, derived from regression on adults. Informational estimate, not medical advice. Talk to a qualified health professional about your own situation.
Worked examples
These examples are verified: each one is an automated test case that the live calculator must reproduce exactly.
Example 1
Inputs: Units = Metric (kg, cm); Sex = Male; Weight (kg, or lb) = 70; Height (cm, or in) = 175.
| Result | Value |
|---|---|
| Lean body mass | 56 kg |
| Body fat mass | 14 kg |
Example 2
Inputs: Units = Metric (kg, cm); Sex = Female; Weight (kg, or lb) = 60; Height (cm, or in) = 165.
| Result | Value |
|---|---|
| Lean body mass | 44.9 kg |
| Body fat mass | 15.1 kg |
The first line is the headline result (lean body mass). Below it the lean Body Mass Calculator lists body fat mass, which describe the same case from other angles. IEEE-754 double precision; shown to 1 decimal place unless stated.
What it estimates
Lean body mass is everything that is not fat: muscle, bone, organs and water. The 56 kg result implies 20% body fat (14 ÷ 70). It's an estimate based on height and weight, not a body-composition scan.
Accuracy
Formulas ignore muscularity: a very muscular person will have more lean mass than predicted. DEXA scans, skinfold calipers and bioimpedance scales give better measurements. This is an estimate only.
How the result changes with weight
Holding every other input at the first worked example, this table changes only weight. It shows how sensitive the answer is to that one value; each row was produced by running this calculator.
| Weight | Lean body mass | Body fat mass |
|---|---|---|
| 35 | 41.8 kg | -6.8 kg |
| 70 | 56 kg | 14 kg |
| 140 | 84.5 kg | 55.5 kg |
| 280 | 141.5 kg | 138.5 kg |
What happens with invalid input
These messages are produced by the calculator itself, so you know what to fix.
- Weight (kg, or lb): entering "0" shows "Weight (kg, or lb) must be at least 20." beside that field and no result.
Choosing between the Lean Body Mass Calculator and similar calculators
Each row shows what a related calculator on this site asks for and what it returns, so you can pick the one that matches your question.
| Calculator | You enter | It returns |
|---|---|---|
| [FFMI Calculator](/health/ffmi/) | weight, height and body fat | FFMI |
| [Center of Mass Calculator](/science/center-of-mass/) | masses and x positions | Center of mass (x) |
| [Molar Mass Calculator](/science/molar-mass-calculator/) | chemical formula | Molar mass |
| [Mass Percent Calculator](/science/mass-percent-calculator/) | mass of component and total mass | Mass percent |
| [Pace Calculator](/fitness/pace-calculator/) | distance and distance unit | Pace per km |
Background: fitness estimates
Fitness formulas are estimates whose accuracy depends on the input. One-rep-max formulas such as Epley and Brzycki give different answers, and predictions from hard sets of a few repetitions are better than from sets of ten or more. Age-based maximum heart rate formulas can be off by 10 to 30 beats a minute for an individual; Tanaka's 208 − 0.7 × age is generally preferred to 220 − age but is still an estimate.
Pace models built from a race result assume a maximal effort and work best for distances from about 5 km to the marathon. Use the output as a guide, not a prescription.
Assumptions and limitations
- Estimate only
- Not a diagnosis
Estimates from formulas describe averages. They are not a training or medical prescription; check with a qualified professional before changing your exercise or diet.
If a required value is empty, not a number, or outside its allowed range, the form marks that field with a message and shows no result instead of a misleading number. The automated checks deliberately try invalid entries for weight (kg, or lb) to confirm this.
Frequently asked questions
What is a healthy body fat percentage?
Roughly 10 to 20% for men and 18 to 28% for women, depending on age.
Is lean body mass the same as muscle?
No, it includes bone and organs.
Why use this formula?
It needs only height and weight.
What does the Lean Body Mass Calculator calculate?
Estimate lean body mass with the Boer formula. It returns Lean body mass and Body fat mass.
What formula does the Lean Body Mass Calculator use?
Men: LBM = 0.407w + 0.267h − 19.2; Women: LBM = 0.252w + 0.473h − 48.3 (w in kg, h in cm). Boer's equation, derived from regression on adults.
What do I need to enter in the lean Body Mass Calculator?
You enter Units, Sex, Weight (kg, or lb) and Height (cm, or in).
How is the result rounded or limited?
IEEE-754 double precision; shown to 1 decimal place unless stated. Estimate only.
What are the limits of this calculator?
Estimate only. Not a diagnosis.
What does the “Units” option change?
It sets how the lean Body Mass is worked out. The choices are Metric (kg, cm) and Imperial (lb, in).
What is an example of a lean Body Mass result?
With units Metric (kg, cm), sex Male, weight (kg, or lb) 70 and height (cm, or in) 175, the lean body mass is 56 kg.
Where does the method come from?
The method follows: Boer P, Am J Physiol 1984;247:F632–F636.
Can I rely on this calculator for a decision?
Estimates from formulas describe averages. They are not a training or medical prescription; check with a qualified professional before changing your exercise or diet. For this calculator in particular: Estimate only.
Related calculators
- FFMI Calculator — Fat-free mass index and its height-normalized value.
- Center of Mass Calculator — Center of mass of point masses in one or two dimensions.
- Molar Mass Calculator — Molar mass and mass percent composition of a chemical formula.
- Mass Percent Calculator — Mass percent of a component in a mixture or compound.
- Pace Calculator — Pace and speed from a distance and a time.
- One Rep Max Calculator — Estimate your one-repetition maximum from a heavier set.
Sources
- Boer P, Am J Physiol 1984;247:F632–F636
Content last reviewed 2026-11-04. Formulas and worked examples are checked by automated tests against independently computed values.