What a DEXA scan shows about your body, and what it costs

Quick answer: A DEXA scan is a quick, very low-dose X-ray that shows what your body is made of: how much fat, muscle and bone you have, and where it sits. People get one for two main reasons. Doctors use it to check bone strength and catch thinning bones before they break. And people who care about their health use it to see their fat and muscle, which a bathroom scale can’t tell apart. It takes about 10 to 30 minutes, you stay dressed, and it costs $65 to $249 at clinics that publish a price.

One machine, two different pictures

There are actually two kinds of DEXA scan, and it helps to know which one you’re getting.

Think of the DEXA machine as a camera. The bone density scan is a close-up of your hip and spine. The body composition scan is a full-length photo of you from head to toe.

Same camera, very different pictures. A close-up of your hip tells you nothing about your belly fat, and the full-length shot isn’t sharp enough to judge your bones the way a doctor needs. Many clinics that advertise “a DEXA scan” mean the body composition one, so if bones are what you care about, ask for the hip and spine scan by name.

How the scan works

DEXA (also written DXA) stands for dual-energy X-ray absorptiometry. A source under the table sends a very weak X-ray beam up through your body at two different energies, and a detector above you measures how much gets through.

Why two energies? Picture shining two colors of light through stained glass. Each type of glass dims each color by a different amount, so comparing the two shadows tells you what the glass is made of. DEXA does the same thing with bone, fat and lean tissue.

You lie on an open table in your clothes, minus anything metal, and stay still for about 10 to 30 minutes. Nothing goes over your face and it’s quiet. The dose is tiny, less than a tenth of a standard chest X-ray, though you should tell the staff first if you are or might be pregnant.

Which scan are you booking?

What a DEXA scan costs

At the clinics we track that publish a price, a DEXA scan costs $65 to $249, and a typical price is about $140. You usually pay for it yourself, with no membership needed, which makes it one of the easiest ways to try longevity testing.

If your doctor orders a bone density scan because you meet the screening criteria, insurance often covers it, and Medicare covers one every 24 months for people who qualify. Body composition scans are usually self-pay. Many clinics also let you book DEXA and a VO2 max test in the same visit. For more on what clinics charge, see how much longevity clinics cost.

Prices change over time, so check with the clinic before you book.

Reading a body composition report

This is the report most longevity clinics hand you, and it’s where DEXA beats a bathroom scale. Two people can weigh exactly the same and carry very different amounts of fat and muscle. The scan shows you which is which, and later, whether it’s changing.

The headline numbers are your body fat percentage and your lean mass. Lean mass is everything that isn’t fat or bone, which is mostly muscle but also includes your organs and water. That’s worth remembering when it jumps around between scans.

Most reports also break things down by region. Arm and leg lean mass is the line doctors often look at as a muscle measure, for example when checking for muscle loss with age. Many reports also estimate visceral fat, the fat packed around your organs deep in your belly. In one large study, the DEXA estimate lined up closely with MRI. If you’d like a simple way to keep an eye on it at home between scans, see visceral fat and waist measurement.

You’ll see a whole-body bone number too, but it isn’t the one used to diagnose osteoporosis. For that you need the hip and spine scan.

There’s no single “good” body fat number on a DEXA report, because reference ranges vary by machine maker. The comparison that means the most is you against your own last scan.

Reading a bone density report

First, the two words you’ll see on a bone report.

Osteoporosis means your bones have become thin and fragile on the inside, so they break much more easily. A small fall that would just bruise most people can break a hip or wrist. It usually causes no pain or symptoms until a bone breaks, which is why a scan is the way to find it early.

Osteopenia, or low bone density, is the step before. Your bones are thinner than normal, but not yet thin enough to be called osteoporosis. It’s a heads-up, not a diagnosis of disease.

Your result comes as a T-score. Think of it as how your bones compare with a healthy young adult’s: zero means the same, and the more negative the number, the thinner your bones. Drag the marker below to see how the ranges work.

Women before menopause and men under 50 usually get a Z-score instead, which compares you with people your own age and sex.

A normal score is good news, but it isn’t the whole picture. In one study of older women, about 3 in 4 fractures happened in women whose scan did not show osteoporosis, partly because there are so many more people in that group. That’s why doctors read bone density alongside your age, past fractures, medicines, balance and strength.

Why your numbers can move when you didn’t

Some of the change between two scans is real. Some is just the scan.

Water is the big one. In one study, drinking about a liter of water raised measured lean mass by nearly 2 pounds within an hour. No new muscle, just water. A large meal or a hard workout right before can shift things too.

The machine matters as well. Two brands of DEXA machine can read the same spine quite differently, in one study by up to 20%, which is bigger than most of the change you’re hoping to see. So a scan at a new clinic isn’t a fair “after” picture for one you had somewhere else.

The fix is simple: go back to the same place and the same machine, at the same time of day, with the same routine beforehand. Skip calcium supplements for 24 hours before a bone scan. And keep your full reports, not just the app summary, so you or your doctor can compare later. There’s more on this in baseline testing vs retesting.

What DEXA can’t tell you

A DEXA scan can show that your bone density is low, but not why. Working that out takes a conversation and blood tests with your doctor.

It also can’t tell you how strong or fit you are. Lean mass is how much muscle you have, not what it can do, which is why many clinics pair DEXA with a VO2 max test or a grip strength test. And it isn’t a scan of your organs. Looking for things like tumors is a different kind of test, covered in full-body MRI vs blood biomarkers.

Who tends to get each scan

The bone density scan is part of regular care for a lot of people. National guidelines recommend it for women 65 and older, and for younger women past menopause who have extra risk. Your doctor may also suggest it if you take long-term steroids or have broken a bone in a minor fall. Medicare covers one every 24 months for people who qualify.

The body composition scan is popular with people who want to see what’s under their weight. Maybe you’re starting a strength or nutrition plan and want a “before” picture, or your weight has held steady but you suspect you’re losing muscle. It’s most useful when you plan to scan again, so you can see the change.

Questions to ask before you book

1. Is this the hip and spine bone scan, the whole-body scan, or both?
2. Will my next scan be on the same machine?
3. How should I prepare, and will it be the same next time?
4. Who goes over the results with me?