Your body fat percentage, and whether it is normal
Estimate your body fat percentage in seconds with the US Navy method — the most common tape-measure approach. You just measure your neck and waist (and hip for women) plus your height. We give you the percentage, your category and, if you add weight, your fat and lean mass.
US Navy tape-measure estimate. Margin of error ±3-4% vs DEXA. Not a medical diagnosis.
That number is only today
In the app you watch it move: weigh-ins, progress photos and the trend of the last weeks in one chart.
Start tomorrow: weigh yourself when you get up, before breakfast, and photograph the first plate of the day.
7 days free · No card · Private
How is body fat calculated?
The US Navy method estimates body fat from body circumferences and height, using a formula validated against hydrostatic weighing. Men need neck and waist; women also need hips, because fat distribution differs enough that one equation cannot cover both. It is not a body scan: expect roughly 3-4 percentage points of error against a DEXA. What it is very good at is consistency — measured the same way each time, the trend it draws is reliable even when the absolute number is a little off, and the trend is what you actually act on.
Normal body fat percentage by age and sex
Here sex and age really do change the range, unlike BMI. Women naturally carry 10 to 13 points more essential fat, and the healthy band rises with age because muscle is lost. The same 25 % is normal at 65 and high at 25.
| Age | Men | Women |
|---|---|---|
| 20 – 39 | 8 – 20 % | 21 – 33 % |
| 40 – 59 | 11 – 22 % | 23 – 34 % |
| 60 – 79 | 13 – 25 % | 24 – 36 % |
Source: Gallagher et al., American Journal of Clinical Nutrition (2000), ranges linked to a healthy BMI. These are reference ranges for healthy adults, not a diagnosis or individual advice.
FAQ
What body fat percentage is healthy?
It depends on sex. In men, a fitness range sits around 14-17% and the healthy range roughly 10-20%; in women, around 21-24% for fitness and 18-28% healthy. Below about 5% in men and 12% in women is essential fat, and going near it is not a goal, it is a risk.
How do I measure the neck and waist properly?
Neck: just below the larynx, tape angled slightly downwards at the front. Waist: at navel height in men, at the narrowest point in women. Tape snug but not compressing, at the end of a normal exhale. Measure at the same time of day, ideally before eating.
Is the US Navy method reliable?
For tracking progress, yes — it is consistent and repeatable, which is what matters. For a precise absolute number, no method short of DEXA or hydrostatic weighing qualifies, and even those disagree with each other by a couple of points.
How much fat can I lose in a month?
A healthy pace is around 0.5-1% of body fat a month while holding on to muscle. Faster than that and you are almost certainly losing lean mass too — which lowers your expenditure and makes the next month harder.