Apple Watch Workouts to Intervals.icu: Upload FIT Files

By Josep Mampel Marques, updated November 11, 2026

To put Apple Watch workouts into Intervals.icu, convert them to FIT files and upload them. The upload announcement on the Intervals.icu forum says you can upload .fit files for completed activities with the Upload button at the top of the calendar page, and that zip files are supported. FitMigrate makes the FIT files in your browser from your Apple Health export.zip, with the GPS route, heart rate, distance and calories each workout recorded. These forum posts are the only documentation we found, and some are years old, so the screens may differ today.

Make the FIT files

1. On your iPhone: Health, your picture, Export All Health Data. The taps are in how to export all Apple Health data.
2. Open the export.zip in FitMigrate on a computer.
3. Click Download all workouts as FIT (zip), or FIT on single workouts.

Upload them to Intervals.icu

1. Sign in to Intervals.icu in a browser and open the calendar.
2. Click the Upload button at the top of the calendar page.
3. Select FIT files, or a zip. The forum says all the files found in a zip are imported.
4. Open one imported activity and check sport, date, route and heart rate before you upload the rest.

The announcement also says you can download the original uploaded file from the activity's data page, which helps if you want to confirm what was imported.

Large histories

In a forum thread about uploading a large batch, one user trying to upload more than 1,800 workouts from a Mac reported a network error after about 150 to 200 files and a 20 MB limit on zip uploads. The site's developer suggested uploading the files to Dropbox and turning on the Download Activities option in the Dropbox area of the settings page, so that Intervals.icu pulls the files. That reply was about Strava export files, but the same route applies to any activity files. Because that is a user report and an answer in a thread, test with a modest batch first.

What the files include

Each FIT file holds one session with a sport, start time, duration, distance, calories, per-second GPS points with elevation when the watch recorded a route, and heart rate samples. Each workout is a single lap, and splits, power and cadence are not included. A forum user points out that Apple Health does not store some fields that other devices record, such as power, so FIT files from other devices are the better source for those. For Apple Watch workouts, the FIT file is as complete as the Apple Health data allows.

Avoid double entries

If you already send Apple Watch workouts to Intervals.icu through Strava, Garmin or an app, a workout can end up in two places. We did not find a statement in the forum posts about how uploads that match existing activities are treated, so upload only the period you are missing. Sort the files by their date-based names to pick them.

Health metrics are different

Intervals.icu also stores wellness data. A forum admin mentions a wellness CSV upload and API support for wellness fields in a thread about Apple Health integration. The CSV format is not covered here, so check the Intervals.icu forum for the required columns before trying. FitMigrate's CSV files have the columns start date, end date, value, unit and source, which are not necessarily what that upload expects.

Limits of this approach

• FitMigrate does not log in to or send data to Intervals.icu. Files stay on your device until you upload them yourself.
• It is a snapshot. New workouts need a new export or a syncing app.
• Some indoor workouts have no route; they still get time and heart rate.

For the same method with another service, see Apple Health to Strava.