You can get your body fat percentage measured through several methods, ranging from a free tape-measure calculation at home to a clinical DEXA scan starting around $100. The right choice depends on whether you need a quick estimate or a precise baseline for tracking changes over time. Each method trades off convenience against accuracy, so understanding what you’re actually getting from each one matters.
Body fat percentage is worth knowing because it tells you something BMI cannot. BMI frequently misclassifies muscular people as overweight, and people with a normal BMI but elevated body fat (a pattern called normal weight obesity) may carry significantly increased risk of metabolic syndrome, type 2 diabetes, and cardiovascular disease without realizing it. A 2025 study in the Annals of Family Medicine found that body fat percentage was a far better predictor of 15-year mortality risk than BMI in adults aged 20 to 49.
The Navy Method: Free and Surprisingly Useful
The simplest way to estimate your body fat is with a flexible tape measure and the U.S. Navy circumference formula. For men, you measure your neck at the base (just below the Adam’s apple) and your waist at the narrowest point above the hip bones, which for most men is at the navel. For women, you add a hip measurement taken at the widest point of the glutes, with feet together.
The formulas use the logarithms of these circumference ratios along with your height to produce a body fat estimate:
- Men: BF% = 86.010 × log10(waist − neck) − 70.041 × log10(height) + 36.76 (all in inches)
- Women: BF% = 163.205 × log10(waist + hip − neck) − 97.684 × log10(height) − 78.387
You don’t need to do the math yourself. Dozens of free online calculators plug these formulas in for you. The margin of error is wider than clinical methods, typically 3 to 5 percentage points, but for a zero-cost method you can repeat weekly, it’s a reasonable starting point. Consistency matters more than perfection: measure at the same time of day, in the same spot, pulling the tape snug but not tight.
Smart Scales and Handheld Devices
Bioelectrical impedance analysis (BIA) is the technology inside body composition scales and handheld monitors. These devices send a tiny electrical current through your body and estimate fat mass based on how quickly the signal travels. Lean tissue, which contains more water, conducts electricity faster than fat.
BIA devices are affordable and convenient, but they’re sensitive to conditions that shift your body’s water balance. Exercising before a reading changes cutaneous blood flow, skin temperature, and electrolyte levels on the skin surface, all of which directly affect the measurement. Dehydration, a heavy meal, or even a hot shower can skew results. International guidelines recommend fasting for 4 to 8 hours before a BIA test and avoiding alcohol, though one study found that consuming a small, low-calorie amount of food and drink had minimal impact on healthy individuals.
If you use a BIA scale at home, the most reliable approach is to weigh yourself first thing in the morning, after using the bathroom, before eating or drinking. The absolute number may be off by several percentage points compared to a DEXA scan, but if you measure under the same conditions each time, you can track trends reliably.
DEXA Scans: The Clinical Standard
Dual-energy X-ray absorptiometry, commonly called DEXA, is widely considered the most practical gold-standard method for body composition. Originally designed for bone density testing, DEXA uses two low-dose X-ray beams to distinguish bone, lean tissue, and fat throughout your entire body. It also shows you exactly where your fat is distributed, which is useful because visceral fat around the organs carries more health risk than subcutaneous fat under the skin.
A DEXA scan takes about 10 minutes. You lie still on a table while the scanner arm passes over you. There’s no water submersion, no breath-holding, and the radiation exposure is minimal, roughly equivalent to a day of natural background radiation. Research in the American Journal of Clinical Nutrition found that DEXA was the only technique that met strict precision benchmarks for fat mass measurement across age groups, with a coefficient of variation around 1.17%.
DEXA scans are available at university research labs, sports medicine clinics, and a growing network of consumer wellness centers. Pricing starts around $100 per scan, and companies like Fitnescity offer access through over 400 partner locations across the United States. No referral is needed at most consumer-facing locations. If you’re investing in a scan primarily to track progress, spacing them 3 to 6 months apart gives your body enough time to show meaningful change.
Hydrostatic (Underwater) Weighing
Hydrostatic weighing was the original laboratory method for body composition and remains highly accurate. The principle is straightforward: fat is less dense than water, so it floats, while lean tissue is denser and sinks. By comparing your weight on land to your weight fully submerged, the test calculates your body density, which is then converted to a body fat percentage.
During the test, you sit on a specialized scale inside a large water tank. You submerge completely, exhale as much air as possible from your lungs, and hold still while your underwater weight is recorded. The test is repeated three times and the results are averaged. The residual air left in your lungs after a full exhale is measured separately and factored into the equation.
Hydrostatic weighing is accurate, but it’s not especially comfortable or convenient. You need to be willing to dunk underwater and blow out all your air, which some people find stressful. It’s typically available only at university exercise science labs or specialized fitness facilities, and scheduling can be limited. For most people, DEXA provides comparable accuracy with a much simpler experience.
Air Displacement (Bod Pod)
The Bod Pod uses the same density-based principle as underwater weighing but replaces water with air. You sit inside an egg-shaped chamber while it measures the volume of air your body displaces. Combined with your weight, this gives your body density and, from there, your fat percentage. The test takes a few minutes and requires no submersion.
One tradeoff: research shows that air displacement plethysmography has slightly wider variability in fat mass measurements than other lab methods, with a coefficient of variation around 2.13% compared to under 1.4% for most other techniques. It’s still far more precise than a home scale, but if you’re choosing between a Bod Pod and a DEXA scan at similar price points, DEXA edges ahead on reliability for fat mass tracking.
Skinfold Calipers
Skinfold testing uses calipers to pinch and measure the thickness of fat beneath the skin at several body sites, typically the chest, abdomen, thigh, triceps, and subscapular area. The measurements are entered into equations that estimate total body fat. When performed by a trained technician, skinfold testing is reasonably accurate and very affordable. Many personal trainers and university fitness centers offer it for free or at minimal cost.
The catch is that accuracy depends heavily on the person doing the pinching. An experienced tester using consistent technique can track your changes over time with solid reliability. An inexperienced one can easily introduce errors of several percentage points. If you go this route, try to use the same tester each time.
What the Numbers Mean
There is no universally agreed-upon “normal” range for body fat, but a large 2025 study using U.S. national survey data defined useful thresholds. For men, body fat at or above 25% was classified as overweight, and 30% or above as obese. For women, the cutoffs were 36% for overweight and 42% for obese. These numbers reflect the natural difference in essential fat between sexes: women carry more essential fat in breast tissue, hips, and around reproductive organs.
Competitive athletes often sit well below these ranges. Male endurance athletes may carry 6 to 13% body fat, while female athletes typically range from 14 to 20%. For general fitness, most men fall in a healthy range around 10 to 20%, and most women around 18 to 28%. Body fat also naturally increases with age, so a 55-year-old at 22% body fat is in a different physiological context than a 25-year-old at the same number.
Getting the Most Accurate Result
Whichever method you choose, preparation and consistency matter more than the method itself. For BIA devices, fast for at least 4 hours, avoid alcohol the day before, skip your workout beforehand, and measure at the same time of day each session. For DEXA or Bod Pod, wear lightweight clothing without metal (zippers, underwire) and stay well hydrated in the days leading up to the test, though you don’t need to fast.
The single most important rule is to compare like with like. A DEXA reading and a BIA reading will almost certainly give you different numbers for the same body on the same day. That doesn’t mean one is “wrong.” It means each method has its own systematic bias. Pick one method, stick with it, control the conditions, and track changes over time. The trend line is what matters, not any single reading.