Number One Body Fat Calculator
Choose metric or imperial, then enter a few tape measures. We estimate body fat with the US Navy method and cross-check it with a BMI-based formula — in your browser, nothing uploaded.
Tape snug, not tight. Neck just below the larynx. Waist at the navel for men, at the narrowest point for women. Hip at the widest part of the seat — the Navy formula uses it for women.
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FitnessTape measures of neck, waist, and hip. Usually the closer of the two simple estimates.
Uses BMI, age, and sex only. Handy as a check, less sensitive to muscle.
Background
Body fat percentage is the share of your mass that is fat, not the rest — muscle, bone, organs, water. Unlike BMI, it tries to separate those. The catch: the gold-standard scans (DEXA, Bod Pod, underwater weighing) need a clinic. What we can do at home is estimate, with formulas that stay honest about being estimates.
The headline figure uses the US Navy / Hodgdon circumference method: a tape around the neck and waist (and hip for women), plus height. It is one of the more reliable simple methods because it sees shape, not just scale weight. The second figure is Deurenberg’s 1991 equation — BMI, age, and sex. It needs no tape, but it cannot tell a rugby player from someone with little muscle. Skinfold calipers can be better in trained hands; they are fiddly to do well on yourself, so we leave them out.
Women carry more essential fat than men — for hormones and reproductive health — so their healthy window sits higher. Fat also tends to rise with age even in active people. An often-cited set of adult ranges (Gallagher) is roughly 8–19% for men aged 20–39, 11–21% at 40–59, and 13–24% from 60; for women, 21–32%, 23–33%, and 24–35% in those same bands. “Athletic” and “fitness” bands used on the chart above are tighter than those health windows — they describe typical sports physiques, not a medical must.
Height does not get its own target percentage. A taller person at 22% simply carries more kilograms (pounds) of fat than a shorter person at 22%. What height does change is how that fat is distributed and how clothes fit. Waist size, how you train, and how you feel still tell more than any one percentage.
Tape estimates can sit a few points off a DEXA scan. Hydration, a full stomach, and where you place the tape all move the result. Very low body fat is not automatically healthier — essential fat is there for a reason — and a “higher” band is a prompt to look at habits, not a verdict. If the figure worries you, take it to a qualified clinician.
Lifestyle
Lasting change is almost never a crash diet or a week of punishment in the gym. Bodies respond better to routines you can keep: enough food to fuel the day, movement you actually enjoy, sleep, and a bit of patience. The cards below are general tips, not a plan — and they are not a substitute for medical advice, especially if you have an eating disorder, are pregnant, or live with a long-term condition.
A modest energy gap works better than cutting whole food groups. Build plates around vegetables, protein, and fibre; drink water first; keep treats in the picture so the plan does not snap. Walk more weeks than you sprint. Strength work two or three times a week helps you keep muscle while the number on the scale eases down. Aim for roughly half a kilogram (about 1 lb) a week, not overnight.
Add nourishing extra rather than only extra sugar: nuts, dairy or fortified alternatives, olive oil, eggs, beans, and an additional snack. Pair that with resistance training so new weight is not only fat. Eat on a regular rhythm even when appetite is low, and give yourself time — sudden gain is as brittle as sudden loss. If food has become frightening or you are losing weight without trying, ask for clinical help.
Move most days in a way that raises your pulse and still leaves you able to talk. Sit less. Eat a mix of plants, protein, and foods you like, without moralising every plate. Sleep enough that the next day is possible. Go easy on alcohol and ultra-processed defaults. Progress is the week you can repeat, not the day you were perfect.
