Body Fat Percentage Calculator

This calculator estimates your body fat percentage using the U.S. Navy method, a practical approach based on circumference measurements. While it’s not as precise as a DEXA scan, it offers a useful, repeatable way to track trends over time with only a tape measure. You’ll enter your height, neck, and waist measurements—and if you’re female, hip circumference as well. The result provides an estimate of body fat as a percentage of total body weight, which can help you gauge changes during nutrition or training plans.

Why track body fat? Body weight alone doesn’t distinguish between fat and lean mass. Two people can weigh the same but carry very different body compositions. Monitoring estimated body fat gives more insight into whether changes on the scale reflect fat loss, muscle gain, or water fluctuations. For best accuracy, measure under consistent conditions: ideally in the morning, before eating, and with the tape placed at consistent anatomical landmarks each time.

The Navy method uses logarithmic equations derived from population studies. It considers that waist (and hip for women) circumferences correlate with abdominal fat, while neck circumference helps account for build. As with any field method, individual variation exists. Use the estimate to guide decisions alongside performance markers, photos, and how your clothes fit—not as the sole indicator of progress.