Accuracy and precision answer different questions
Accuracy concerns agreement with an appropriate reference method. Precision concerns repeatability when a measurement is repeated under comparable conditions. A method can be repeatable while giving a systematically different answer from another method.
An advertised percentage error is not useful without knowing the measurement, population, scanner, protocol and statistical definition. We do not give one universal accuracy percentage for every DEXA result. Ask the clinic for precision information relevant to the measurement you want to follow.
DEXA vs InBody, smart scales and other methods
Choose a method around the decision you need to make, then keep the method consistent for follow-up. Different technologies can produce different estimates on the same day. That does not mean your body changed between tests.
| Method | Basis of measurement | Main comparison limit |
|---|---|---|
| DEXA | Low-dose X-ray attenuation; estimates fat, lean soft tissue and bone mineral | Scanner, analysis, region definitions and preparation matter. |
| InBody and other BIA devices | Electrical impedance interpreted through a device model | Device and testing conditions affect estimates. No ionising radiation. |
| Home smart scales | Usually bioimpedance plus device-specific prediction | Not interchangeable with a DEXA percentage or another scale model. |
| BOD POD | Air displacement estimates body volume and density | A different model of body composition; follow its clothing and testing protocol. |
| Skinfolds | Caliper measurements at defined sites | Technique, sites and the chosen prediction equation matter. |
| 3D optical scanning | External body shape and model-based estimates | External geometry is not a direct measurement of internal tissue compartments. |
Why two DEXA reports can differ
Before comparing headline values, check manufacturer, model, software, units and whether both examinations cover the same region. A total lean-soft-tissue value and a lean-plus-bone-mineral value are different quantities even if both headings use the word lean.
Ask how preparation and positioning were handled. Food, fluid, physical activity and analysis decisions can complicate interpretation. The most useful comparison includes both complete reports and the clinic’s assessment of whether the methods are comparable.
Scanner-specific report labels ↗
How large does a change need to be?
Ask the facility for its least significant change, or LSC, for the measure concerned. The calculator below illustrates the relationship between precision error and a comparison threshold. It cannot establish the cause or clinical importance of a change.
Is the change larger than measurement variation?
Use the same measure, units, scanner and comparable preparation. The 2% starting value is an educational lean-mass example, not your clinic’s measured precision. For fat mass, the ISCD minimum acceptable precision example is 3%. Replace this with the clinic’s own precision or ask for its LSC directly.
Enter positive values to calculate an illustrative threshold.
This approximation converts relative precision using the first value. An exceeded threshold is not proof of muscle gain, fat loss or a clinically important change. Hydration and protocol differences still matter. Values stay in your browser.
Source: ISCD precision assessmentWhat to ask before paying for a comparison
Tell the provider what you hope to learn. “Has this change been large enough to measure on your equipment?” is more useful than asking whether DEXA is generally accurate. If you previously used another method, ask whether this visit should start a new baseline.
A more detailed test is not automatically a better choice for every goal. Agree on how the finding will be used and who will explain it. For a bone health question, ask about a diagnostic bone density examination and a GP follow-up rather than choosing a body composition package from a feature list.
Common questions
Is DEXA always more accurate than InBody?
There is no universal comparison that covers every device, population and measurement. Ask which method is appropriate for your question and use consistent conditions for follow-up.
Can I convert my smart-scale body fat result into a DEXA result?
We do not provide a conversion factor. Different methods and models can have different biases, and a fixed adjustment may mislead.
Does a higher lean-mass result prove muscle gain?
No. Lean soft tissue includes more than muscle. Comparability, preparation and measurement variation need to be considered.
BEFORE YOU BOOK
Find the right appointment.
For diagnostic bone density, start with your referring doctor. For body composition, compare what is included and who will explain the report.
Browse prices in all six cities ↗
Search the national scan directory ↗
Only your city choice is remembered in this browser. No location permission or email address is needed.