Calculate your body fat %, lean mass and fat mass using the accurate US Navy circumference method. Free tool for Irish athletes & fitness enthusiasts.
Your Measurements US Navy Method
Please fill in all required fields with valid values.
No thanks — skip and see results
Want the plan that actually moves this number? The free Day One pack and the protein targets are the whole method — no call, no signup, nothing to book.
Body Fat Categories
How to Measure Correctly
Waist — Measure at the narrowest point, usually just above the navel. Breathe normally; do not suck in.
Neck — Measure just below the larynx (Adam's apple) with the tape sloping slightly downward at the front.
Hip (women) — Measure at the widest point of the hips/buttocks. Keep the tape horizontal.
Within a few percent, which is enough for the only thing that matters: the direction it moves. Scales that flash a body fat number at you are guessing from water content and are less reliable. Measure the same way, same time of day, once a fortnight.
For most men, the mid-teens looks lean and is sustainable; low single digits is a photoshoot, not a lifestyle. For most women, add roughly ten points. Health markers matter more than the number.
Because you are losing fat and holding muscle, which is the goal. Recomposition shows up in the tape and the mirror well before it shows up on the scale.
About the author
Keith O’Beirne went from 90kg to 72kg around a full-time job and two kids, after paying a personal trainer to learn the basics. He is not a doctor, dietitian or coach and does not sell coaching — he writes No Nonsense Fitness to give away what he paid to learn, free, with no ads, no subscriptions and no commission on any link. Based in Dublin.
This is the same circumference method the U.S. Navy uses for fitness assessments. Full methodology, including accuracy versus DEXA, is in our methodology page.