📏 Body Fat %

About this calculator

Body fat percentage tells you how much of your weight is fat versus everything else (muscle, bone, water) — a much better health gauge than BMI alone. Enter measurements like waist, neck, hips, height, weight, age, and sex, and the calculator estimates your body fat % using the U.S. Navy method. It also shows how your result stacks up against healthy ranges for your age and sex. No calipers or fancy equipment needed — just a tape measure.

Tip: measure first thing in the morning on the same day each week, and don't obsess over a single reading — trends over months matter more than any one number.

How to read your body fat result

Body fat percentage describes what share of your weight is fat tissue; the rest is muscle, bone, organs and water. The method behind this estimate matters as much as the number. Tape based formulas such as the US Navy method typically land within about 3 to 4 points of a laboratory measurement. Skinfold calipers depend heavily on the skill of the person pinching. Bathroom scales that estimate body fat from electrical impedance can swing several points between morning and evening as your hydration changes, and even DEXA scans, the usual reference standard, carry their own small errors. For context, commonly used ranges for men are 6 to 13 percent for athletes, 14 to 17 for the fit, 18 to 24 for average, and 25 or above for obese. For women the ranges run higher for healthy physiological reasons: 14 to 20 for athletes, 21 to 24 for the fit, 25 to 31 for average, and 32 or above for obese. A single reading from any one method is a rough position, not a measurement to the decimal point. The trend from the same method, under the same conditions, is the figure worth trusting.

A worked example

Take a man of 45, 180 cm tall, weighing 90 kg. His neck measures 40 cm and his waist, taken at the level of his navel, measures 96 cm. The Navy formula combines those figures and returns about 23 percent body fat. That places him at the top of the average range for men. Translated into tissue, roughly 21 kg of his 90 kg is fat mass and about 69 kg is lean mass. Suppose his bathroom scale shows 25 percent one evening and 22 percent the next morning: both readings are circling the same truth, and the difference is hydration, not a sudden change in his body. If he remeasures in eight weeks, fasted, at the same time of day, with the tape at the same spot, a move from 96 cm to 92 cm at the waist would mean real progress whatever any single percentage claims.

Common mistakes

• Measuring the waist at the belt line or the narrowest point instead of at navel level, or pulling the tape tight enough to compress the skin. Both errors shrink the waist and flatter the result.
• Comparing numbers across methods as if they were interchangeable. A DEXA 24 percent and a scale 24 percent are estimates from different models and will routinely disagree by several points.
• Testing impedance scales after training, eating, drinking alcohol or a hot shower. Anything that shifts body water shifts the reading, sometimes by 3 points or more.
• For women, skipping the hip measurement or taking it at a different spot each time. The female Navy formula needs the hip at its widest point, recorded the same way every time.
• Chasing decimal places. A change smaller than about 2 points is within the noise of most home methods and proves nothing either way.

Frequently asked questions

What is a healthy body fat percentage?

For men, roughly 14 to 24 percent spans the fit to average range, with 25 or above classed as obese. For women, roughly 21 to 31 percent covers fit to average, with 32 or above classed as obese. Athletes sit lower, and healthy targets rise somewhat with age.

Why does my scale disagree with this calculator?

They measure different things with different assumptions. Your scale passes a small current through your body and guesses from water content, so hydration moves its answer by several points. This calculator uses body measurements and population averages. Expect disagreement; follow one method's trend instead of mixing them.

How often should I measure my body fat?

Every two to four weeks is enough. Real body fat changes slowly, perhaps half a percent a month during steady fat loss, while measurement noise between sessions can be 2 points or more. Measure at the same time of day, in the same state, and record waist size alongside.

Can my BMI be normal while my body fat is high?

Yes, and it is common enough to have a nickname: skinny fat. Someone with little muscle can sit comfortably inside the healthy BMI band while carrying a high share of fat, especially around the waist. Resistance training and adequate protein, rather than more weight loss, are the usual answer.