You can measure body fat percentage using methods ranging from a simple tape measure at home to clinical scans that cost a few hundred dollars. The right choice depends on whether you need a precise number or just want to track changes over time. Each method has trade-offs between accuracy, cost, and convenience.
DEXA Scans: The Clinical Gold Standard
Dual-energy X-ray absorptiometry, commonly called a DEXA scan, is considered the most accurate widely available method. You lie on a table for about 10 minutes while a low-dose X-ray beam passes over your body, distinguishing between fat, lean tissue, and bone. The scan also shows exactly where fat is distributed, so you can see, for example, whether you carry more visceral fat around your organs than subcutaneous fat under your skin.
DEXA is far more precise than calipers or bioelectrical impedance scales. The main downsides are cost (typically $75 to $150 per scan at a clinic or university lab) and availability. You’ll need to find a sports medicine center, university health program, or specialized fitness facility that offers it. If you want a single, reliable baseline number, DEXA is the best option.
Bod Pod and Underwater Weighing
Both of these methods measure body density, then use that to calculate fat percentage. Hydrostatic (underwater) weighing requires you to sit on a submerged scale and exhale all the air from your lungs while fully underwater, which some people find uncomfortable. The Bod Pod uses air displacement instead: you sit inside a sealed, egg-shaped chamber for a few minutes while sensors measure how much air your body displaces.
The Bod Pod carries an error range of roughly 1 to 2.7 percentage points and is considered equally accurate to underwater weighing while being much faster and easier. Both methods are available at university exercise science labs and some fitness centers, with prices similar to DEXA scans.
Bioelectrical Impedance (Smart Scales)
Most consumer “body fat scales” use bioelectrical impedance analysis, or BIA. You stand barefoot on the scale (or grip handheld electrodes), and a weak electrical current passes through your body. Fat tissue resists electricity because it contains very little water, while muscle and organs conduct it easily because they’re rich in water and electrolytes. The scale measures that resistance and plugs it into a formula to estimate your fat-free mass, then calculates fat percentage from there.
The accuracy issue is real. A 2021 observational study found that body composition scales measured total weight well but were not reliable for body composition. Your hydration level, whether you just exercised, and even the temperature of your skin can shift readings. That said, research from the Journal of Strength and Conditioning Research found that hydration status had minimal effect on BIA accuracy in college athletes, so the impact of day-to-day water fluctuations may be smaller than commonly believed.
The practical value of a smart scale isn’t the absolute number. It’s the trend. If you weigh yourself under the same conditions each time (same time of day, same hydration habits), you can track whether your body fat percentage is going up or down over weeks, even if the specific number is off by several percentage points.
Skinfold Calipers
Skinfold testing uses a special set of calipers to pinch and measure the thickness of fat beneath the skin at specific body sites. The widely used Jackson-Pollock 7-site method measures folds at the chest, abdomen, thigh, tricep, subscapular (below the shoulder blade), suprailiac (just above the hip bone), and midaxillary (on the side of the torso). Those measurements go into an equation that estimates total body fat.
Calipers are inexpensive (a decent pair costs $10 to $30), but accuracy depends heavily on the person doing the measuring. A trained technician who takes measurements at exactly the right sites and pinches consistently will get much better results than someone doing it alone for the first time. If you go this route, having the same person measure you each time matters more than finding a new tester who might be slightly more skilled.
The U.S. Navy Tape Measure Method
You can estimate body fat at home with nothing more than a flexible tape measure and a calculator. The U.S. Navy method uses circumference measurements plugged into a logarithmic formula. Men need three measurements: neck circumference (at the base, just below the Adam’s apple), waist circumference (at the navel), and height. Women need those same three plus hip circumference (at the widest point of the glutes, feet together).
The formulas look like this:
- Men: Body fat (%) = 86.010 × log10(waist − neck) − 70.041 × log10(height) + 36.76, with all measurements in inches
- Women: Body fat (%) = 163.205 × log10(waist + hip − neck) − 97.684 × log10(height) − 78.387
You don’t need to calculate this by hand. Dozens of free online calculators will do it for you. The Navy method isn’t as precise as a DEXA scan, but it’s free, repeatable, and good enough to track progress if you measure at the same spots each time and pull the tape to the same snugness.
What the Numbers Mean
Body fat percentage varies significantly between men and women because women carry more essential fat for reproductive and hormonal functions. Here are the general classification ranges:
- Essential fat: 3 to 5% for men, 9 to 11% for women
- Athletes: 6 to 13% for men, 12 to 19% for women
- General fitness: 14 to 17% for men, 20 to 24% for women
- Obese: 25%+ for men, 30%+ for women
Essential fat is the minimum your body needs to function. Dropping below those thresholds causes hormonal disruption, immune suppression, and organ damage. Most people aiming for a lean, healthy physique land comfortably in the fitness or athlete range without needing to push to extremes.
Getting Consistent Results
No method is perfectly accurate, so consistency in how and when you measure matters more than which method you pick. For BIA scales, step on at the same time of day, ideally in the morning before eating. For calipers and tape measures, use the same anatomical landmarks each time. For any method, avoid measuring right after intense exercise, which temporarily shifts fluid between tissues.
Testing frequency also makes a difference. If you’re actively trying to lose fat, measuring every 4 to 6 weeks gives your body enough time to show real change. If you’re building muscle, every 6 to 8 weeks is a better window, since lean mass accumulates slowly. For general maintenance, every 2 to 3 months is plenty. Testing more frequently than every few weeks tends to amplify normal fluctuations into false signals, making small day-to-day noise feel like meaningful change.
Choosing the Right Method for Your Goals
If you want a single accurate snapshot, a DEXA scan or Bod Pod gives you the most trustworthy number. If you’re tracking progress over months of training or dieting, a consumer BIA scale or tape measure used consistently under the same conditions will show you the trend reliably, even if the absolute number is off. If you have access to a skilled trainer or exercise physiologist, skinfold calipers offer a solid middle ground between precision and affordability.
The most useful body fat measurement is one you’ll actually repeat. A $20 scale used every month under identical conditions tells you more about your progress than a $150 DEXA scan you get once and never follow up on.