Body Composition Calculator
Estimate your body fat percentage, BMI, and health risk ratios using four proven methods. Compare results side by side — medication-aware context for GLP-1 and TRT users.
Measure at navel level
Measure at widest point
Below the Adam's apple
BMI
Overweight
Body Fat (Navy Method)
Fitness
Waist-to-Hip Ratio
Low risk
Waist-to-Height Ratio
Healthy
Estimated lean mass
Estimated fat mass
Understanding Each Method
BMI
+ Quick, requires only weight and height
- Doesn't distinguish fat from muscle — overestimates for muscular people
Best for: General population screening
Navy Method
+ More accurate than BMI, accounts for body shape
- Requires waist, hip, and neck measurements
Best for: TRT and fitness users who need body fat tracking
Waist-to-Hip Ratio
+ Good predictor of cardiovascular risk
- Doesn't estimate total body fat
Best for: Health risk assessment
Waist-to-Height Ratio
+ Simple, strongly correlated with metabolic risk
- Doesn't estimate body composition
Best for: Quick health screening
Frequently Asked Questions
Why doesn't BMI work well for people on TRT?+
BMI only considers weight relative to height. TRT typically increases lean mass, which makes BMI overestimate fatness. The Navy Method body fat % is more useful for people building muscle.
How accurate is the Navy Method?+
Within ±3-4% of DEXA scan results for most people. It's the most practical method that doesn't require specialized equipment. Named after the US Navy's physical readiness test.
How do I measure my waist correctly?+
Stand relaxed (don't suck in). Measure at the level of your navel with a flexible tape measure. Keep the tape snug but not compressing the skin.
How often should I track body composition?+
Weekly for general tracking, but expect fluctuations. Monthly averages are more reliable. Measure at the same time of day (morning before eating) for consistency.
What's a healthy body fat percentage for men on TRT?+
Most TRT-focused guidelines target 12-20% body fat. Athletic goals are typically 10-15%. Below 8% is competition-level and hard to maintain long-term.
Does GLP-1 medication affect these calculations?+
GLP-1 medications cause weight loss that includes both fat and lean mass. Tracking body fat % (not just weight) helps ensure you're preserving muscle. Adequate protein intake (0.7-1g per lb bodyweight) is critical.
Data Sources
- Hodgdon & Beckett (1984) — US Navy body fat estimation formula
- WHO (2008) — Waist-to-hip ratio guidelines for cardiovascular risk
- Ashwell & Hsieh (2005) — Waist-to-height ratio as health risk predictor
Related Tools
Doseline provides informational tools only. It is not a medical device and does not provide medical advice. Always consult a qualified healthcare provider.
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