You can find your body fat percentage using methods that range from a free calculation at home to a professional scan costing around $185. The right choice depends on how precise you need to be and what you plan to do with the number. Here’s how each method works, what it actually measures, and how accurate you can expect it to be.
What Counts as a Healthy Body Fat Percentage
Before you measure, it helps to know what the numbers mean. The American Council on Exercise places the average non-athlete range at 25% to 31% for women and 18% to 24% for men. Body fat below 14% for women or 6% for men is considered dangerously low and carries real health risks. The overall U.S. average sits at about 39.9% for women and 28.1% for men, so falling below those numbers puts you in better-than-average territory even if you’re not in the “fitness” category.
These ranges exist because men and women carry fat differently. Women need more essential fat for hormonal function and reproductive health. Two people at the same weight can have very different body fat levels depending on how much of their weight is muscle versus fat, which is exactly why body fat percentage tells you something your bathroom scale can’t.
The Free Method: US Navy Formula
The simplest way to estimate body fat at home requires only a flexible tape measure. The US Navy body fat formula uses two circumference measurements for men (neck and waist) and three for women (neck, waist, and hips), along with your height.
Here’s where to measure:
- Neck: at the base, just below the Adam’s apple, at the narrowest point above the trapezius muscle
- Waist: the narrowest point above your hip bones (for most men, this is at the belly button; for women it varies)
- Hips (women only): stand with feet together and measure the widest part of the glutes
The formula plugs these numbers into a logarithmic equation that estimates body fat within about 3 to 4 percentage points of more accurate methods. You don’t need to do the math yourself. Dozens of free online calculators will run the Navy formula instantly once you enter your measurements. It won’t catch changes in visceral fat or tell you about muscle imbalances, but it’s a solid starting estimate that costs nothing.
Smart Scales and Handheld Devices
Body composition scales and handheld analyzers use a technology called bioelectrical impedance. They send a tiny, painless electrical current through your body and estimate fat based on how much resistance the current encounters. Muscle, which holds more water, conducts electricity well. Fat does not.
The problem is that your hydration level directly affects the reading. Dehydration causes the scale to overestimate body fat, while drinking a lot of water beforehand leads to an underestimate. Exercise, heat exposure, sweat loss, and even the type of fluid you drink (water versus a sports drink) all shift the results. After drinking fluids, it can take one to two hours for absorption to stabilize, meaning the timing of your last glass of water matters more than you’d expect.
These devices work best for tracking trends over time rather than pinpointing an exact number. If you use one, measure under the same conditions every time: first thing in the morning, after using the restroom, before eating or drinking, wearing minimal clothing, with the scale on a hard, flat floor. Consistency in conditions matters more than the individual reading.
Skinfold Calipers
Skinfold testing uses calipers to pinch and measure the thickness of fat beneath the skin at specific sites on your body. The most thorough version, the Jackson-Pollock 7-site method, takes measurements at the chest, abdomen, thigh, tricep, subscapular (below the shoulder blade), suprailiac (above the hip bone), and midaxillary (mid-side of the torso).
You can buy calipers for under $10, but accuracy depends heavily on technique. A trained tester who pinches the same spot, at the same angle, with the same pressure will get repeatable results within 3 to 4 percentage points of lab methods. Doing it yourself introduces more error because some sites are hard to reach and harder to pinch consistently. If you go this route, having a personal trainer or exercise physiologist take the measurements gives you a much more reliable baseline than self-testing.
Bod Pod: Air Displacement Testing
The Bod Pod is a capsule-shaped chamber that calculates your body density by measuring how much air your body displaces. The test takes about 10 minutes. You sit inside the sealed chamber while a diaphragm creates small pressure changes, and the system measures your body volume by comparing the chamber’s air volume when empty versus when you’re seated inside. Combined with a precise weight measurement, it calculates your density and splits it into fat mass and fat-free mass.
Clothing and hair significantly affect results. You’ll need to wear minimal, form-fitting clothing like compression shorts or a swimsuit (no padding or wires), and a swim cap to compress air trapped in your hair. Jewelry and glasses must be removed. Bod Pod testing is available at universities, sports performance centers, and some hospitals, typically costing $40 to $75 per session.
DEXA Scan: The Most Detailed Option
A DEXA scan (dual-energy X-ray absorptiometry) is widely considered the gold standard for body composition. Originally developed for bone density testing, it uses low-dose X-rays to distinguish between fat, lean tissue, and bone throughout your entire body. A scan runs around $185 at dedicated testing facilities, though prices vary by location.
What makes DEXA unique is the level of detail. Beyond a single body fat number, you get regional composition showing fat and muscle distribution across your arms, legs, and trunk. It measures visceral fat, the fat surrounding your internal organs that’s linked to heart disease and diabetes risk. It also tracks muscle mass by region, which can reveal imbalances between your left and right sides. The scan itself is painless, takes about 10 to 15 minutes, and involves lying still on a table while the scanner passes over you.
For most people, a DEXA scan makes sense as a baseline measurement or a periodic check-in every few months rather than a frequent tracking tool. The cost adds up quickly if you’re scanning monthly.
Getting Consistent Results With Any Method
Whichever method you choose, the conditions surrounding your measurement matter almost as much as the method itself. Weigh and measure first thing in the morning after using the restroom, before eating or drinking. Wear the same clothing (or none) each time. Use the same device and the same scale placement on a hard, flat surface.
If you’re using a smart scale or calipers to track changes, avoid comparing a morning reading to an evening one, or a well-hydrated reading to a post-workout one. The number will bounce around based on fluid intake, recent meals, and exercise. Weekly or biweekly averages, taken under identical conditions, give you a far more honest picture of whether your body composition is actually shifting.
Stick with one method over time rather than switching between them. A smart scale and a DEXA scan will almost certainly give you different absolute numbers, but each can reliably show the direction of change if you use it consistently. The trend line matters more than any single reading.