Body Fat Calculator

When to use this

BMI told you a number, but you suspect it is not the whole story. Maybe you lift weights and your BMI says "overweight" even though you can see your abs. Or maybe your BMI is normal but you feel softer than you would like. Body fat percentage is the metric that fills in the gap — it tells you what fraction of your total weight is fat versus lean mass (muscle, bone, water, organs). Two people at the same height and weight can have dramatically different body fat percentages and, by extension, very different health profiles.

This calculator offers two estimation methods. The U.S. Navy tape-measure method uses neck, waist, and hip circumference along with height to estimate body fat. It was developed for military fitness assessments and remains one of the most accessible methods that does not require specialized equipment — just a flexible tape measure. The BMI-based method derives an estimate from your height, weight, age, and sex using a regression formula. It is less precise but requires no measurements beyond what a bathroom scale and a wall ruler provide.

Neither method replaces clinical tools like DEXA scans or hydrostatic weighing, which measure body composition directly. But for tracking trends over time — seeing whether your training and nutrition are moving the needle — a consistent tape-measure estimate taken under the same conditions each week is genuinely useful. The trend matters more than any single reading.

Good to know

The Navy method is surprisingly accurate for most people. Studies show it typically falls within 3–4 percentage points of DEXA scan results for individuals in the average body fat range. Accuracy decreases at the extremes — very lean athletes and individuals with obesity may see larger discrepancies.

Measure consistently for useful data. Take circumference measurements first thing in the morning, before eating, at the same anatomical landmarks each time. Waist at the navel, neck at the narrowest point below the Adam's apple, hips at the widest point. Small measurement inconsistencies can swing your result by several percentage points.

Healthy ranges differ by sex and age. Women naturally carry more essential fat than men — about 10–13% versus 2–5%. A body fat percentage of 20% means something very different for a 25-year-old male athlete than for a 50-year-old woman. The categories below reflect these differences.

Essential fat is not optional. Dropping below essential fat levels (roughly 5% for men, 12% for women) can disrupt hormone production, immune function, and organ protection. Competitive bodybuilders reach these levels temporarily for competition but do not sustain them year-round.

Body fat is one piece of the puzzle. Where you carry fat matters as much as how much you carry. Visceral fat around the organs (reflected in waist circumference) is more strongly linked to metabolic disease than subcutaneous fat under the skin. A healthcare provider can help you interpret your results in context.

Quick Reference

Category	Men	Women
Essential Fat	2 – 5%	10 – 13%
Athletes	6 – 13%	14 – 20%
Fitness	14 – 17%	21 – 24%
Average	18 – 24%	25 – 31%
Above Average	25%+	32%+