How to measure body fat: 7 methods compared
- A DEXA scan gives the most precise number most people can get, for about the price of a dinner out.
- For weekly tracking at home, a tape measure or a smart scale is enough.
- Smart scales swing with water. Measure at the same time every day and trust the weekly average.
- Consistency beats precision. Pick one method and stay with it.
Every method estimates. None of them cut you open and weigh your fat. The question is how close each one gets, what it costs, and how easy it is to repeat.
| Method | Precision | Cost | Best for |
|---|---|---|---|
| DEXA scan | High | Paid per scan at a clinic or lab | A baseline every 3 to 6 months |
| Bod Pod | High | Paid per test at a lab or gym | A baseline if no DEXA near you |
| Hydrostatic weighing | High | Varies, few places offer it | Research settings |
| Skinfold calipers | Medium, depends on skill | Low | Weekly home tracking |
| Tape (Navy method) | Medium | Very low | Weekly home tracking |
| Smart scale (BIA) | Low to medium | Low to medium | Daily trend with no effort |
| Photos and mirror | Low | Free | Seeing change you can't feel |
DEXA scan
DEXA uses low-dose X-rays to split your body into fat, lean tissue and bone. It also shows where your fat sits, arm by arm and leg by leg. The scan takes about 10 minutes lying on a table. Clinics, sports labs and some gyms offer it.
Get one if you want a real baseline. Repeat every 3 to 6 months. Scan at the same time of day, fasted, with the same clinic if you can.
Bod Pod
You sit in a sealed egg-shaped chamber. It measures how much air you push out, which gives your body volume, then your density, then your body fat. It's quick and close to DEXA on most people. It's harder to find.
Hydrostatic weighing
You breathe out and go fully under water while sitting on a scale. It was the lab standard for decades. It's not pleasant and few places still offer it. Skip it unless a university lab near you runs it.
Skinfold calipers
You pinch a fold of skin and fat at set points on the body and read the thickness. A formula turns the sum into body fat. In trained hands calipers are close to lab methods. In untrained hands they can miss by a lot.
The fix is practice. Use the same sites, the same side of the body, and take each pinch three times. See our caliper picks.
Tape measure (Navy method)
You measure neck and waist (plus hips for women) and plug them into a formula. It's what our calculator uses. It's easy to repeat and costs almost nothing. It misses more on very lean or very muscular people.
Smart scales (bioelectrical impedance)
A small, safe current runs through your feet. Fat slows it more than muscle and water do, so the scale guesses body fat from the speed. The problem is water. Drink a liter of water, sweat through a workout, or eat a salty dinner, and your number moves.
Smart scales are still worth it for the habit. Step on every morning after the bathroom, before food, and look at the 7-day average. See our smart scale picks.
Photos
Take front, side and back photos every 4 weeks. Same light, same spot, same clothes. Photos catch changes that numbers miss, like a tighter waist while the scale sits still.
Which method should you use?
Here's the setup we'd pick for most people:
- One DEXA scan to start, if there's one near you.
- A tape measure or calipers once a week for the trend.
- A smart scale every morning if you like data. Ignore single readings.
- Log it all in one place. Our tracking sheet does the math and charts it for you.