How often should I remeasure body fat with this calculator?

Recheck every 2–4 weeks under the same conditions—morning, fasted, and before workouts—to track meaningful trends without daily noise.

Are tape-based body fat methods accurate enough?

When you measure consistently, circumference formulas stay within about 2–3 percentage points of DEXA. They are reliable for seeing direction of change.

Body Fat Percentage Calculator

Auto-calculate as I type

Results update automatically after you stop typing. Uncheck to use the "Calculate" button manually.

Basic measurements

Unit system

Metric (kg, cm)

Imperial (lbs, ft/in)

Sex

Required for accurate body fat calculation.

Age

Age in years (18-100).

Height

ft in

Enter your height in centimeters or feet and inches.

Weight

lbs

Enter your weight in kilograms or pounds.

Waist circumference

Measure at the narrowest point, usually just above the belly button.

Neck circumference

Measure just below the Adam's apple for men, or at the narrowest point for women.

Hip circumference (females only)

Measure at the widest point of the hips.

Understand your body fat readings

We blend the U.S. Navy circumference method with the YMCA formula to give you a realistic range. Averaging two validated approaches smooths out tape-measure variability and rewards consistent measurement technique.

Waist and neck drive accuracy

Measure at the narrowest point after a relaxed exhale. Record neck just below the larynx and hips at their fullest point if you are female for the Navy method to stay precise.

Category cues

Categories follow American Council on Exercise guidance. Use them to spot trends, not to shame progress—body fat is one data point in a larger health picture.

Pair with circumference tracking

Add thigh, hip, and arm measurements monthly. The more consistent data you log, the clearer your recomposition pattern becomes.

Explore related guidance

Common questions

How often should I remeasure body fat with this calculator?: Recheck every 2–4 weeks under the same conditions—morning, fasted, and before workouts—to track meaningful trends without daily noise.
Are tape-based body fat methods accurate enough?: When you measure consistently, circumference formulas stay within about 2–3 percentage points of DEXA. They are reliable for seeing direction of change.

Expert review & trust signals

Measurements and interpretations reviewed by Chiamaka Bello, CSCS, CES, a certified strength and conditioning specialist with clinical exercise physiology experience. Last methodology review: 30 June 2024.

References: American Council on Exercise body fat categories, U.S. Navy Physical Readiness Program, and International Journal of Obesity circumference research.