Compatible measurements
Which Withings measurements can be sent to Garmin?
A Withings scale can produce more data than Garmin Connect can receive. BodyRelay sends compatible values only and shows the excluded measurements before transfer.
The six compatible values
Weight · BMI · Body fat · Muscle mass · Bone mass · Body water
| Measurement | Withings availability | Garmin | BodyRelay handling | Known limit |
|---|---|---|---|---|
| Weight | Weigh-in value and unit | Timestamped weight | Normalised unit, source time preserved | Display rounding can differ |
| BMI | Provided or derivable | Body mass index | Sent when available or derivable | Depends on profile height |
| Body fat | Scale and weigh-in dependent | Body-fat percentage | Percentage normalised | Missing when not measured at source |
| Muscle mass | Scale dependent | Compatible mass value | Mass normalised before sending | Garmin format is less detailed |
| Bone mass | Scale dependent | Compatible mass value | Mass normalised before sending | Never invented when missing |
| Body water | Water percentage when available | Body percentage | Bounded and normalised percentage | Availability varies by scale |
Why can a value be missing?
Availability first depends on the scale model, profile and weigh-in. A scale that does not produce bone mass cannot transfer it. Garmin Connect also does not accept every value specific to the Withings ecosystem.
BodyRelay does not invent missing values. The preview marks a measurement as compatible, ignored or absent. This prevents an excluded value from looking like a successful transfer.
Values that are not transferred
Measurements such as ECG, vascular age, pulse-wave velocity, scale heart rate or segmental analysis are not sent by BodyRelay. They do not match the weigh-in format Garmin can receive through this flow.
Units and timestamps
BodyRelay preserves the time of the source measurement and normalises units before sending. The weigh-in should therefore appear at the right time in Garmin regardless of the display unit selected in Withings. Display rounding can differ between applications without changing the source value.
History and duplicate protection
A fingerprint is associated with every source measurement. When a known weigh-in is found again, BodyRelay detects it and reduces the risk of a repeat send; an uncertain result remains subject to reconciliation rather than being presented as guaranteed. History keeps the useful technical state without retaining measurements indefinitely.
How to verify the result
After your first test, compare a recent weigh-in in both applications. Check weight, time and each available body-composition value. If something is missing, start with the BodyRelay preview: it shows whether the source did not provide the value or Garmin could not receive it.
Withings: no direct connection · Garmin: weight data. The matrix describes the tested BodyRelay contract.
Withings → Garmin
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