Input parameters
Example data table
Use this example table to understand typical inputs and outputs. Values are illustrative and not individual recommendations.
| Age | Sex | Height | Weight | Waist | Neck | Hip | Estimated body fat % | Lean mass (kg) |
|---|---|---|---|---|---|---|---|---|
| 28 | Male | 180 cm | 80 kg | 82 cm | 38 cm | — | 15.8% | 67.3 |
| 42 | Female | 165 cm | 68 kg | 78 cm | 34 cm | 98 cm | 30.2% | 47.5 |
| 55 | Male | 175 cm | 90 kg | 100 cm | 40 cm | — | 27.9% | 64.9 |
Age-based reference data
1. Typical healthy body fat ranges by age
| Age group | Sex | Healthy range (%) | Borderline high (%) |
|---|---|---|---|
| 18–39 | Male | 8–19 | 20–25 |
| 18–39 | Female | 21–32 | 33–38 |
| 40–59 | Male | 11–21 | 22–26 |
| 40–59 | Female | 23–33 | 34–39 |
| 60+ | Male | 13–24 | 25–28 |
| 60+ | Female | 24–35 | 36–40 |
2. Example lean mass index bands
Lean mass index is lean mass divided by height squared, similar to body mass index but focused on muscle and organ mass.
| Sex | LMI (kg/m²) | Interpretation |
|---|---|---|
| Male | 14–16 | Lower lean mass for adult height |
| Male | 16–19 | Typical recreational trainee range |
| Male | 19–22 | Very muscular, trained individuals |
| Female | 11–13 | Lower lean mass for adult height |
| Female | 13–16 | Typical recreational trainee range |
| Female | 16–19 | Very muscular, trained individuals |
3. Example goal body fat ranges by training profile
| Profile | Sex | Common goal range (%) | Usage |
|---|---|---|---|
| General lifestyle | Male | 15–22 | Balance health, energy, and adherence |
| General lifestyle | Female | 22–30 | Comfortable range for most adults |
| Strength / physique | Male | 10–15 | Off-season strength or physique focus |
| Strength / physique | Female | 18–25 | Off-season physique improvement phase |
| Endurance | Male | 8–16 | Performance and weight-sensitive sports |
| Endurance | Female | 18–26 | Running, cycling, and similar disciplines |
4. Example weekly change guidelines by target
These guideline rates assume stable lean mass and focus on sustainable, long-term body fat and lean mass management.
| Goal direction | Typical weekly rate (kg) | Comment |
|---|---|---|
| Moderate fat loss | 0.25–0.75 | Common range for most adults |
| Aggressive fat loss | 0.75–1.00 | Short phases, higher monitoring recommended |
| Recomposition focus | -0.10–0.10 | Slow weight change, training and protein prioritized |
| Lean mass oriented gain | 0.10–0.40 | Useful for strength or physique phases |
Formulas used
1. Body mass index
BMI is calculated from height and weight:
BMI = weight_kg / (height_m²)
2. Deurenberg age-adjusted body fat
This equation incorporates BMI, age, and sex to estimate body fat:
BF% = 1.2 × BMI + 0.23 × age − 10.8 × sex − 5.4
where sex = 1 for males, 0 for females
3. US Navy circumference method
Uses logarithms of circumference measurements to estimate body fat. All lengths are handled internally in inches.
Male:
BF% = 495 / (1.0324 − 0.19077 × log10(waist − neck)
+ 0.15456 × log10(height)) − 450
Female:
BF% = 495 / (1.29579 − 0.35004 × log10(waist + hip − neck)
+ 0.22100 × log10(height)) − 450
4. Lean and fat mass
Lean mass = body weight × (1 − BF% / 100)
Fat mass = body weight − lean mass
These equations are population-based estimations. Individual results can differ from clinical measurements.
How to use this calculator
- Choose sex and enter your current age in years.
- Select your preferred unit system: metric or imperial values.
- Enter height and weight carefully, avoiding rounding too aggressively.
- Measure waist, neck, and hip circumferences at consistent landmarks.
- Pick the primary method or keep the combined recommended option.
- Optionally set a training profile to refine interpretation.
- Enter goal body fat and timeline for planning guidance.
- Press calculate, then export CSV or PDF for tracking changes.
This calculator is for educational planning only. Always discuss major body composition changes with professionals.
Frequently asked questions
1. How accurate is this body fat and lean mass calculator?
It uses population formulas from research and circumference equations, so results are estimates, not diagnoses. Hydration, measurement error, ethnicity, and athletic build can shift accuracy. Use trends, not single readings.
2. Which method should I choose for the primary result?
For mixed goals, keep the average of Navy and Deurenberg, which balances circumference and BMI information. Choose Deurenberg when you lack tape measurements. Choose Navy when BMI seems misleading for muscular or very lean bodies.
3. Can I use this tool while bulking or cutting?
Yes. During fat-loss or muscle-gain phases, the calculator helps track lean mass stability and fat trends. Compare exports over weeks. Large lean mass drops during dieting may suggest an overly aggressive deficit, training issues, or inadequate protein intake.
4. Why does my result differ from DEXA or calipers?
Different methods measure different aspects of body composition and use different reference data. DEXA and high-quality caliber measurements are usually closer to true values. Online tools approximate, so some divergence is expected. Use each method consistently when tracking change.
5. What is a sensible goal body fat percentage?
Many generally healthy ranges fall between about 15–22 percent for men and 22–30 percent for women, depending on age and sport. Very low targets require medical supervision and careful periodisation, especially for competitive physique or endurance athletes.