How long does Apple Watch keep HealthKit data?

Question

Created Jun ’23

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I would like to create an Apple Watch only app that queries data such as blood oxygenation, heart varibility, number of steps, energy consumed, and other data of a similar nature recorded over the past month and performs calculations on them. I read from the HealthKit documentation that Apple Watch synchronizes data with iPhone and periodically deletes older data, and that I can get the date from which the data is available with earliestPermittedSampleDate(). Is there a risk that in general, by making queries to retrieve data up to a month old, the data will no longer be available? I need the app to work properly without needing an iPhone.

Answered by DTS Engineer in 790601022

In general, Apple Watch keeps HealthKit data for about a week. For some data types, the retention time can be longer, and so you might see the data is still there after a week. We don't have a complete list about the retention time of those data types to share. You might consider doing your own testing on the data types you are interested in, if you need the information.

Best,
——
Ziqiao Chen
 Worldwide Developer Relations.

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Answer 1

simonfromhelix OP

Jul ’23

Sorry, I've had a look and can't find the docs on this but essentially, my understanding is that the Apple Watch holds at least the past 7 days of Health data.

If you had an app running on the Watch you could consider using background execution to cache entries and extend that window.

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Answer 2

simonfromhelix OP

Jun ’24

I believe this may have changed with WatchOS 11.

Presumable this was done to allow for the new Vitals app and also Workout training loads to look at the longer 28 day trends and identify differences.

I'll do some testing and try to come back with some actual available timescales for this against Health types:

Heart Rate
HRV
Blood Oxygen Saturation
Body Temperature
Steps
Activity
Workouts

Might take me a few weeks incase I have to have had WatchOS 11 installed for the elapsed time period to see the data!

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Answer 3

DTS Engineer OP

Apple

Jun ’24

Recommended

In general, Apple Watch keeps HealthKit data for about a week. For some data types, the retention time can be longer, and so you might see the data is still there after a week. We don't have a complete list about the retention time of those data types to share. You might consider doing your own testing on the data types you are interested in, if you need the information.

Best,
——
Ziqiao Chen
 Worldwide Developer Relations.

0

Answer 4

simonfromhelix OP

Jun ’24

UPDATE

From testing on an Apple Watch Series 6 running WatchOS 11.0 Beta 1, it appears there are no significant changes to the availability of past Health data on Apple Watch.

Unfortunately I've just found that in general you can only rely on the past 7 days of Health data being there.

It could be that this changes in a later beta or it could be that the Series 6 Apple Watch (oldest supported by WatchOS 11) behaves differently to maybe 64GB Apple Watches such as the Ultra 2. Regardless, it's not something I would plan for or rely on in WatchOS 11.

If you're still desperate for more Health data either consider a background task and caching it over time, or file a feedback and question how the new Vitals app and also Workout training loads achieve more Health access.

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