Why do my Garmin numbers differ in Apple Health?

A Garmin, Oura or WHOOP number and the same number in Apple Health can disagree, and neither is wrong. Each device measures at its own time of night, with its own formula, and names the result its own way. What matters is how today compares with your own usual on the same device.

• What crosses over to Apple Health
• Why HRV differs between devices
• Why sleep differs
• How to read it

What crosses over to Apple Health

Your tracker's app decides what it writes into Apple Health, and each maker writes a subset. From the makers' own descriptions and independent comparisons we know of, as of October 2026: sleep, heart rate and workouts are the common ones. Oura and WHOOP do not write HRV. Garmin does not write a workout's GPS route. Resting heart rate, respiratory rate and blood oxygen are written by some makers and not others. The Health app shows what any app writes: profile picture, then Apps, then the app's name.

That list is theirs to change, and we have not yet checked it on a real Garmin, Oura or WHOOP account.

Why HRV differs between devices

HRV is the small variation in the spacing between heartbeats, and there is more than one way to turn it into a number. Apple Watch and Apple Health use SDNN. Many rings and straps report RMSSD. The two calculations give different values from the same heartbeats, and devices also measure at different times of night and for different lengths of time. A 45 on one device and a 60 on another say nothing about who is fitter. Compare a device only with itself. More in Apple Watch HRV: what is normal.

Why sleep differs

• Stages are estimates. Wrist and ring devices infer light, deep and REM sleep from movement and heart rate. Different algorithms disagree, sometimes by tens of minutes a night.
• Scores are each maker's own. A "sleep score" or "sleep performance" from one maker is not the same recipe as another's. Apple's own Sleep Score is a separate scale again. See what is a good sleep score.
• Only one source counts per night in Aera. If a watch and a ring both log the same night, Aera picks the fullest one with stages and does not blend them, so the night is never a mixture of two devices.

How to read it

1. Pick one device as your main source for sleep and HRV and stay with it for a few weeks.
2. Look at the trend against your own usual, not at a single night or a number from someone else's device.
3. If you switch devices, expect your usual to shift. Give the new one a couple of weeks before drawing conclusions.

How Aera does this

Get Aera on the App Store

Quick answers

Does Garmin data show up in Apple Health?

Some of it. Garmin Connect can write sleep, heart rate and workouts to Apple Health according to Garmin's own list, but not the GPS route of a workout. What you see depends on the settings you allow in the Garmin app.

Why is my Garmin HRV different from Apple Health?

Different formula and different timing. Apple Health stores HRV as SDNN, while many other devices report RMSSD. The two give different numbers from the same heartbeats, so compare a device only with itself.

Why does my Garmin sleep score differ from my Apple Watch?

Each maker estimates sleep stages with its own algorithm and builds its own score. The scores are not interchangeable, and a gap of a few points or tens of minutes is normal.

Can I use two trackers at once?

Yes, but pick one as your main source for sleep and HRV. Aera reads one source per night for sleep and does not blend two devices.

Related: Aera with Garmin, Oura, WHOOP and other trackers · All guides