Estimate Your Body Fat Percentage

Skinfold measurements (Jackson-Pollock 3-site, mm) - advanced

How This Body Fat Calculator Works

Your body fat percentage is the share of your total weight that comes from fat tissue. This calculator estimates it with four published field methods, all validated against underwater weighing and DEXA, then points out where they agree. The US Navy circumference method uses a tape measure on the neck, waist and hips and is the most accurate no-equipment estimate for most adults (about +-3-4 percentage points of a DEXA scan). The YMCA method needs only a waist tape and a scale. The BMI-based equation estimates body fat from height, weight and age, and the Jackson-Pollock 3-site skinfold method is available when you have calipers.

Because every method is a regression trained on large populations, the four estimates will not be identical. When they land within 2-3 percentage points of each other you can trust the range. When they diverge widely, one input measurement is probably off. This tool is built for tracking change over time on the same person using the same method, which is exactly what all the major fitness organizations recommend.

How to take the measurements

  1. Height: stand straight, barefoot, looking forward.
  2. Weight: weigh yourself first thing in the morning, after the bathroom, on an empty stomach.
  3. Neck: measure just below the larynx (Adam's apple), tape sloping slightly downward to the front, shoulders relaxed.
  4. Waist: men measure at navel level; women at the narrowest point of the torso. Keep the tape level and read after a normal exhale. Do not suck in.
  5. Hips: women only, at the widest point of the hips/buttocks, tape level and parallel to the floor.
  6. Skinfolds: men pinch chest, abdomen and thigh; women pinch triceps, suprailiac and thigh, all on the right side, with a quality caliper. Read ~2 seconds after releasing the trigger, three times per site, and average.

Why AI Chatbots Cannot Replace This Tool

Ask a chatbot for your body fat percentage and it will guess a number, or worse, confidently repeat a fixed rule that ignores your measurements entirely. Body fat equations are sex-specific logarithm regressions with four inputs and set constants; there is no judgment call and no single correct free-form answer. This calculator runs the exact published Hodgdon & Beckett (Navy), YMCA, Deurenberg (BMI) and Jackson-Pollock formulas deterministically, so the same tape measurements always produce the same defensible estimate you can track over time. A language model cannot measure you, and it cannot reliably evaluate the log10 circumference equations either.

How to Use It

  1. Enter your sex, age, height and weight.
  2. Take your neck and waist circumference (and hips for women) with a flexible tape, following the guide above.
  3. Optionally add three skinfold measurements if you own calipers.
  4. Optionally set a target body fat percentage to see the weight you need to reach.
  5. Click Calculate and compare all methods side by side. Use the same method every time to track progress.

Frequently Asked Questions

What is the most accurate body fat calculator?

DEXA scans, BodPod and hydrostatic weighing are the lab standards, but they cost money. At home, the US Navy circumference method (neck, waist, hips plus height) is the most accurate no-equipment estimate, accurate within roughly 3-4 percentage points of a DEXA scan for most adults. The Jackson-Pollock 3-site skinfold method is comparable if you have quality calipers and have practiced the technique.

What is a healthy body fat percentage?

Guidelines vary by sex and age. For men, athletes are typically 6-13%, fitness 14-17%, and acceptable 18-24%. For women, athletes are typically 14-20%, fitness 21-24%, and acceptable 25-31%. Age-adjusted healthy ranges are also shown next to your result. Essential fat is around 3-5% for men and 10-13% for women; dropping below that is unhealthy.

Why do the four methods give different results?

Each formula is a regression trained on a different population using different inputs. The Navy method infers fat from torso shape, YMCA from a single waist-to-weight ratio, BMI-based from body mass index, and skinfolds from directly pinched fat thickness. A spread of 2-3 percentage points is normal. If the spread is large, re-check the most sensitive input (the waist) and remeasure.

Is BMI the same as body fat?

No. BMI only compares weight to height and cannot tell muscle from fat, so a muscular person can have a high BMI and low body fat. Body fat percentage is the more informative number. This tool shows both so you can see how your body fat estimate compares with the BMI shortcut.

How should I measure my waist for consistency?

Stand relaxed, breathe out normally, and keep the tape level with the floor. Men measure at the navel; women at the narrowest point of the torso. Do not pull your stomach in and do not tighten the tape into the skin. Always measure at the same spot, at the same time of day, and take two or three readings that you average.

Can I use this to track progress?

Yes, and that is the best use of any field method. Use the same method, the same tape, the same site and the same time of day each week, and the trend will be far more reliable than any single number. Circumference and skinfold equations measure change well even when their absolute accuracy is +-3-4%. The progress card also shows the exact weight that corresponds to your target body fat.

Does this save or upload my measurements?

Never. Every calculation runs inside your browser; nothing is sent to a server. Open the developer tools network tab while you calculate and you will see no outgoing requests. Your measurements and your privacy stay on your device.