Calculator form
Use body fat percentage when available. It improves lean mass based estimates.
Example data table
| Profile | Age | Height (cm) | Weight (kg) | Body Fat % | LBM (kg) | BMR (kcal/day) | Maintenance (kcal/day) |
|---|---|---|---|---|---|---|---|
| Male Example | 30 | 178 | 80 | 18 | 65.60 | 1,786.96 | 2,769.79 |
| Female Example | 28 | 165 | 62 | 24 | 47.12 | 1,387.79 | 1,908.21 |
| Mixed Goal Example | 42 | 172 | 95 | 28 | 68.40 | 1,847.44 | 2,216.93 |
Formula used
Lean body mass from body fat
LBM = Weight × (1 − Body Fat % / 100)
This is the most direct option when body fat percentage is known.
Boer lean body mass formula
Male: 0.407 × weight + 0.267 × height − 19.2
Female: 0.252 × weight + 0.473 × height − 48.3
James lean body mass formula
Male: 1.10 × weight − 128 × (weight / height)²
Female: 1.07 × weight − 148 × (weight / height)²
Hume lean body mass formula
Male: 0.32810 × weight + 0.33929 × height − 29.5336
Female: 0.29569 × weight + 0.41813 × height − 43.2933
BMR formulas
Katch-McArdle: 370 + 21.6 × LBM
Cunningham: 500 + 22 × LBM
Mifflin-St Jeor: 10W + 6.25H − 5A + s
Harris-Benedict: sex specific equation using weight, height, and age.
Weight is in kilograms, height is in centimeters, age is in years, and calorie outputs are daily estimates.
How to use this calculator
- Select metric or imperial units.
- Enter sex, age, height, and body weight.
- Add body fat percentage for the most direct lean mass estimate.
- Choose a lean body mass method and a BMR formula.
- Select an activity factor to estimate maintenance calories.
- Press the calculate button.
- Review the result cards, comparison tables, and Plotly graph.
- Download your result as CSV or PDF when needed.
FAQs
1. What is lean body mass?
Lean body mass is your body weight without stored fat. It includes muscle, bone, water, organs, and other fat free tissue.
2. Why does this calculator ask for body fat percentage?
Body fat percentage lets the calculator estimate lean body mass directly. When you know that value, lean mass based calorie equations become more personalized.
3. Which lean body mass method should I choose?
Use the body fat method when you trust your body fat reading. Otherwise compare Boer, James, Hume, and the average estimate for a broader view.
4. Which BMR formula is best?
Katch-McArdle works well when lean mass is known. Mifflin-St Jeor remains popular for general estimates. Comparing formulas can show how sensitive your calorie estimate is.
5. Is BMR the same as maintenance calories?
No. BMR estimates calories used at complete rest. Maintenance calories are higher because they multiply BMR by an activity factor.
6. Why are my results different across formulas?
Each equation was built from different research groups and assumptions. Small differences are normal, especially when body composition data is uncertain.
7. Can I use this for weight loss or muscle gain planning?
Yes, as a starting point. Many people adjust calories gradually after tracking body weight, hunger, training performance, and progress over time.
8. Are these results medical advice?
No. These are educational estimates. Speak with a qualified clinician or registered dietitian for medical, athletic, or condition specific guidance.