Where you measure body fat depends on which method you’re using. A tape measure, skinfold calipers, a bathroom scale, and a clinical DEXA scan all target different spots on the body, and each has its own rules for getting a reliable number. Here’s a breakdown of the exact locations for every common method, plus how to get consistent results.
Tape Measure: The US Navy Method
The simplest approach uses a flexible tape measure and a formula developed by the US Navy. The measurement sites differ for men and women.
For men, you need two measurements: neck and abdomen. The neck measurement goes just below the Adam’s apple, on bare skin, keeping the tape level and horizontal all the way around. Be careful not to let the tape ride up onto the shoulder muscles at the back. The abdomen measurement goes straight across the belly button with your arms relaxed at your sides.
For women, you need three measurements: neck, natural waist, and hips. The neck is measured the same way as for men, just below the Adam’s apple. The natural waist is not at your belly button. Instead, it sits at the point of smallest circumference, roughly halfway between your navel and the bottom of your breastbone. If you can’t easily spot the narrowest point, take several measurements at slightly different heights and use the smallest number. The hip measurement wraps around the widest point of your buttocks as viewed from the side.
These circumference values, combined with your height, plug into a formula that estimates body fat percentage. It’s not as precise as clinical methods, but it’s free and easy to repeat at home.
Waist Circumference Alone
Even without calculating a full body fat percentage, waist circumference by itself is a useful indicator of visceral fat, the deep abdominal fat packed around your organs. Two major health organizations recommend slightly different landmarks for where to place the tape.
The World Health Organization says to measure midway between your lowest rib and the top of your hip bone (the iliac crest). To find this spot, press your fingers into your side to locate the bottom edge of your rib cage and the bony ridge of your hip, then mark the halfway point. The National Institutes of Health uses a simpler landmark: directly above the top of the hip bone. Both are valid, but you should pick one and stick with it so your measurements are comparable over time.
Skinfold Calipers: 3-Site and 7-Site Methods
Skinfold calipers pinch a fold of skin and underlying fat at specific spots, then use the thickness to estimate total body fat. The most widely used formulas come from Jackson and Pollock, and they call for measurements on the right side of the body.
The 3-site method uses different locations for men and women. For men: chest, abdomen, and thigh. For women: tricep (back of the upper arm), suprailiac (just above the hip bone), and thigh. This version is quicker and works well for general fitness tracking.
The 7-site method measures all of the following:
- Tricep: back of the upper arm, halfway between the shoulder and elbow
- Subscapular: just below the bottom tip of the shoulder blade
- Chest: a diagonal fold between the armpit and nipple
- Midaxillary: on the side of the torso at the midpoint of the armpit
- Suprailiac: just above the hip bone, slightly forward
- Abdominal: about one inch to the side of the belly button
- Thigh: front of the thigh, halfway between the hip and knee
At each site, you pinch the skin, pull it slightly away from the muscle, and clamp the caliper jaws onto the fold. The reading is taken in millimeters. All seven values get summed and fed into a formula that accounts for age and sex. The suprailiac and abdominal sites together provide a particularly useful estimate of midsection fat distribution.
Caliper Accuracy
Calipers are only as good as the person using them. When trained professionals take the measurements, results typically fall within a few percentage points of clinical methods. Self-administered calipers are far less reliable. One study comparing caliper types found that self-administered devices had individual accuracy swings of plus or minus 7.5 to 8.6 percentage points, while professional-grade digital calipers landed closer to plus or minus 5 to 6.5 points. That gap matters: if your actual body fat is 20%, a self-administered caliper could read anywhere from about 12% to 28%. For tracking trends over time, consistency in technique matters more than the absolute number.
Bioelectrical Impedance Scales and Devices
Bioelectrical impedance analysis (BIA) sends a tiny electrical current through your body and measures how quickly it travels. Fat slows the signal down because it contains less water than muscle, and the device uses that difference to estimate your body composition.
A clinical BIA setup places four electrodes on the body: one on the hand, one on the wrist, one on the foot, and one on the ankle, all on the same side. This gives the current a full path through the torso. Consumer bathroom scales simplify this by putting sensors under your feet only, while handheld devices run the current through your arms only. Both shortcuts mean the signal doesn’t pass through your entire body, which reduces accuracy, especially for estimating trunk fat.
Hydration heavily influences BIA readings. Drinking a large amount of water, exercising, or even eating a meal shortly before stepping on the scale can shift your result by several percentage points. If you use a BIA scale at home, weigh yourself at the same time each day, ideally in the morning before eating or drinking, to get numbers you can meaningfully compare.
DEXA Scans: Full-Body Clinical Measurement
A DEXA (dual-energy X-ray absorptiometry) scan is the closest thing to a gold standard available outside a research lab. You lie on a table while a low-dose X-ray arm passes over your entire body. The scan distinguishes between three tissue types: fat, lean mass (muscle and organs), and bone.
Unlike every other method, DEXA doesn’t rely on a single measurement site. It maps your entire body and breaks down fat distribution by region. The results typically include your total body fat percentage, a visceral fat measurement estimating the internal abdominal fat surrounding your organs, and an android-to-gynoid ratio. That ratio describes whether you carry more fat around your midsection (“apple” shape) or around your hips and thighs (“pear” shape), a distinction that matters for cardiovascular and metabolic risk.
DEXA scans are available at sports medicine clinics, some hospitals, and specialized body composition labs. A single scan typically costs between $50 and $150 out of pocket.
Getting Consistent Results at Home
Whichever method you choose, the measurement protocol matters as much as the measurement site. Small changes in posture, timing, or technique can shift your numbers enough to hide real progress or create the illusion of change that isn’t there.
Always measure on the same side of the body. Professional standards use the right side for skinfold calipers. Stand on both feet with your weight evenly distributed and your gaze straight ahead. Breathe normally and let your arms hang relaxed unless the method calls for a specific arm position. For waist and circumference measurements, don’t suck in your stomach or puff it out. Take each measurement two or three times and use the average.
Time of day, recent meals, hydration, and exercise all affect results, particularly for BIA devices and tape measurements (bloating alone can add an inch to your waist). Measure at the same time of day, under the same conditions, and compare readings taken weeks or months apart rather than day to day. The trend line over several months tells you far more than any single number.