Body girth calculator.
Record measurements across 12 anatomical sites, with optional left/right tracking for limbs and a progress photo per session. Convert between cm and inches, save sessions to your device, and see your trend on a chart. Your data never leaves the browser.
Measurement Session
Optional: body fat % & FFMI
Add sex, height, and weight to also see a Navy-method body fat estimate and Fat-Free Mass Index, computed from the neck/waist/hip values above — nothing else to re-enter. Leave blank to skip; the rest of the calculator works fine without this. The Navy method runs about ±3.5% off hydrostatic weighing — useful for tracking your own trend over time, not as an exact number.
Progress chart
Saved sessions
Why track body girth?
Girth measurements track changes in body size that scales and BMI miss. Two people with the same weight can have very different physiques; girth tells you whether weight changes are in the arms, the waist, or somewhere else entirely.
For athletes, girth is the cheapest reliable indicator of hypertrophy. Bicep girth grows with successful arm training; waist girth shrinks during a successful cut. Combined with body weight, you get a clear signal about whether a training block is working.
For health, waist circumference correlates with cardiovascular risk independent of BMI. Waist-to-hip ratio (WHR) is one of the strongest non-invasive predictors of metabolic disease.
How WHR is calculated
Waist-to-hip ratio is your waist circumference divided by your hip circumference, both measured in the same unit:
WHR = waist ÷ hips
Measure both with a flexible tape pressed flat against the skin without compressing tissue — waist at the narrowest point between the lowest rib and the top of the hip bone, hips at the widest point around the buttocks. Take two readings within 0.5 cm and average them.
Enter waist and hips above and this calculator computes WHR live. If you turn on left/right tracking, it also computes the size difference between sides for bicep, forearm, wrist, thigh, calf, and ankle as you type — those numbers exist only once you enter your own measurements, which is the part a static formula reference can't give you.
Linked calculators
Some measurements feed into formulas. These calculators use the values you've entered above:
- US Navy body fat — uses neck, waist, height (and hips for women)
- Waist-to-hip ratio — uses waist and hips
- Ideal proportions (McCallum) — uses wrist as the baseline
Per-site measurement guides
Detailed instructions for measuring each anatomical site, with anatomical landmarks and common errors:
Sources & standards
This calculator's WHR, Navy body fat, and FFMI computations are drawn directly from the following sources, not secondary calculator sites — each formula and constant was checked against the original publication:
- CDC/NCHS — NHANES Anthropometry Procedures Manual, 2021 edition — general circumference measurement standard source
- American Council on Exercise (ACE) — Anthropometric Measurements guidance — fitness-industry assessment protocol source
- World Health Organization (2008) — Waist Circumference and Waist-Hip Ratio: Report of a WHO Expert Consultation — WHR formula and risk thresholds source
- Hodgdon JA, Beckett MB (1984) — Naval Health Research Center Reports 84-11 (men) and 84-29 (women) — Navy body fat formula, via DTIC source
- Kouri EM, Pope HG Jr, Katz DL, Oliva P (1995). “Fat-free mass index in users and nonusers of anabolic-androgenic steroids.” Clin J Sport Med 5(4):223-8 — FFMI formula and normalization constant, via PubMed source