If you've looked into tracking body fat or muscle properly, you've probably run into two options. A DEXA scan at a clinic, or a body composition scale at home. People search for an "at home DEXA scale" all the time, so it's worth being straight about what each one actually does, what it costs, and where a home scale fits.
The short answer
A home scale is not a DEXA scan and can't replace one. But it does something a DEXA scan can't do, which is track you every day for a one off cost. For most people the best setup is a DEXA scan occasionally as a baseline, and a good home scale in between to see whether things are moving in the right direction.
What a DEXA scan is
DEXA uses two low dose X-ray beams to measure fat, lean muscle and bone in different parts of your body. It's considered the most accurate common method for body composition, and it's the only one that also measures true bone mineral density.
The catch is cost and access. In Australia a body composition DEXA scan typically runs from around $120 to $300 per scan, usually with no Medicare or private health rebate for body composition. You also have to book in, travel to a clinic, and some clinics want a referral. Most people do one or two a year at most.
What a body composition scale does
Body composition scales use bioelectrical impedance analysis, or BIA. A very small, safe electrical current passes through your body. Fat, muscle and water resist that current differently, and the scale uses that resistance plus your height, age and sex to estimate body fat, muscle mass, body water and other measures.
There are two main types, and the difference matters a lot.
4 electrode scales read through your feet only. The current mostly travels up one leg and down the other, so the reading for your upper body is largely an estimate. These are most of the cheap smart scales on the market.
8 electrode scales read through your hands and feet, so the current passes through your whole body including the torso and arms. That gives a much more complete reading and allows segmental results for each arm, leg and the trunk. This is the same approach used by the clinical InBody machines found in gyms and clinics.
So do body fat scales actually work?
Yes, with a caveat. A good 8 electrode scale gives a useful estimate, and it's very good at showing change over time. It is less reliable as a single absolute number, because BIA is sensitive to how hydrated you are.
Things that throw a reading off:
- Weighing straight after training, a sauna, or a big drink
- Being dehydrated, including after alcohol
- Weighing at different times of day
- Cold or very dry feet and hands, which reduce contact
The fix is simple. Weigh at the same time each day, ideally first thing in the morning after the bathroom and before food or exercise. Then watch the trend across weeks, not the number on one morning. Done that way, a good scale tells you whether you're losing fat, holding muscle, or going backwards, which is what most people actually want to know.
Home scale vs DEXA side by side
- Accuracy on a single reading: DEXA is better.
- Bone density: Only DEXA measures true bone mineral density. Scales give a bone mass estimate, which is not a medical bone density test.
- Tracking change: A home scale wins, because you can measure daily under the same conditions and see the trend.
- Cost: One DEXA scan is roughly $120 to $300. A quality 8 electrode home scale costs about the same as one or two scans, and you use it every day for years.
- Convenience: No booking, no travel, 30 seconds in your bathroom.
Who should use which
Get a DEXA scan if you need a precise baseline, you're concerned about bone density, or a doctor or dietitian has asked for one. If bone health is the concern, speak to your GP, since a bone density scan may be covered by Medicare in some circumstances.
Get a home scale if you want to track progress while training or changing your diet, you're working with a PT or coach, or you want to see what's happening between scans without paying for one every month.
Use both if you're serious about it. A DEXA scan once or twice a year as a check, a home scale for the weeks in between.
What to look for in a home scale
- 8 electrodes, hands and feet, not feet only
- Segmental readings for arms, legs and trunk
- App tracking so you can see trends, not just today's number
- Multiple user profiles if more than one person will use it
- Published accuracy data against a clinical reference, not just marketing claims
What we stock
Vectr Medical stocks the Unique range of 8 electrode body composition scales, which the manufacturer rates at 98% or higher correlation with the InBody 270 clinical analyser.
- Unique CF661 Slim, compact 8 electrode scale, $229
- Unique CF669, same 8 electrode accuracy in a standard form, $229
- Unique CM0001 Standing, touchscreen standing analyser for home gyms and clinics, $1,499
Not sure which one suits you? Read our guide to choosing a body composition scale, or browse the full smart scales range.
General information only. A body composition scale is not a diagnostic device and does not measure bone mineral density. If you have concerns about osteoporosis, bone health, or your weight and health, speak to your GP.