Body composition and strength estimates, with the math shown.
Navy and Army tape methods, lean mass and one-rep max. Imperial or metric. Every result shows its formula and its error.
Open the body fat calculator- Height
- 70 in
- Neck
- 15 in
- Abdomen
- 34 in
86.010 × log10(34 − 15) − 70.041 × log10(70) + 36.76
17.5% body fat, ± about 3.5 points
Calculators
- Body fat Percent body fat from a tape measure, your weight or your BMI. 17.5%Navy method: man, 70 in tall, 15 in neck, 34 in abdomen US Navy (DoD)Army 2023 one-siteDeurenberg BMI
- Lean body mass Everything that is not fat, from height, weight and sex. 57.8 to 62.7 kgThree formulas: man, 80 kg, 180 cm BoerJamesHume
- One rep max Your heaviest single from a set of 2 to 10 reps, plus a %1RM load table. 253 to 264 lb225 lb for 5 reps EpleyBrzyckiLombardi
- Bench press Bench max from reps, with a bench-specific fourth equation. 228 to 234 lb185 lb for 8 reps EpleyBrzyckiLombardiMayhew
The Army changed its rule in July 2026
Army Directive 2026-13 dropped the tape-measure body fat test. The only standard now is waist-to-height ratio: waist at the navel divided by height must be under 0.55. At 70 in tall, that means a waist under 38.5 in. Exactly 0.55 does not pass.
Our body fat calculator keeps the 2023 Army formula as a labelled second opinion and shows your ratio next to it. Read how the Navy and Army methods split.
Where each number comes from
Every calculator uses a published equation, named on its page with the source linked. Where sources disagree, the page says so. These are the stated errors you should keep in mind.
| Tool | Method | Source | Stated error or status |
|---|---|---|---|
| Body fat | US Navy / DoD tape | Hodgdon & Friedl, 1999 | SE about 3.2 to 3.7 points |
| Body fat | Army one-site (former) | Army Directive 2023-11 | Rescinded July 2026 |
| Body fat | BMI-based | Deurenberg et al., 1991 | SE 4.1 points |
| Lean mass | Boer, James, Hume | 1984, 1976, 1966 | Up to about 5 kg apart |
| Strength | Epley, Brzycki, Lombardi | 1985, 1993, 1989 | Often 10% off for one lifter |
| Strength | Mayhew (bench only) | Mayhew et al., 1992 | 2 to 10 reps only |
Guides
- Body fat percentage ranges: what the numbers can and cannot tell youPublished body fat percentage ranges explained: the ACE categories, how age, sex and measurement method shift them, and why one number says little.
- Navy vs Army body fat methods: what is differentCompare the US Navy and Army tape methods: what each measures, how the formulas differ, why the Army dropped its tape test in 2026, and what that means.
- How to test your one-rep max safely (or estimate it instead)A practical guide to finding your 1RM: when to estimate from a rep set, how to run a direct test with a spotter, warm-up steps, and when to skip it.