Read an Apple Health export

The export

Getting the file off an iPhone

1. Open the Health app and tap your picture at the top right.
2. Tap Export All Health Data, then Export. It can take several minutes for a few years of data.
3. Save the export.zip to Files, AirDrop it to a Mac, or send it to your own computer. Drop that zip here as it is; there is no need to unzip it.

Why a day's steps can differ from the Health app

An iPhone in a pocket and an Apple Watch on a wrist both count the same walk, and so can a running app or a smart scale's app. The export keeps every source's records separately. Add them all up and that walk is counted two or three times, which is the mistake most scripts and spreadsheets make with this file.

The Health app avoids that by choosing one source for each stretch of time, in the order set under Data Sources and Access. That merge is not written into the export. So VITALS shows, for each day, the single source that counted the most. It never counts anything twice, and it is usually a little under the Health app's figure, because on a day when the watch was off for an hour, Health fills that hour from the phone. Every source added together, or one source alone, is one choice away.

How each kind is summed up

• Things that add up (steps, distance, energy, flights, exercise minutes, water, food) are totalled per day.
• Readings (heart rate, weight, blood oxygen, blood pressure, VO2 max) are averaged per day, with the lowest and highest.
• Sleep is time asleep, across every stage the watch records, and not time in bed or awake. A night belongs to the morning it ends, so sleep from 6 pm onwards counts toward the next day.
• Stand hours count only the hours stood. Other events, such as high heart rate notifications, are counted.
• A day is the date on the record, in the time zone it was recorded in, as Health shows it after a trip.
• Blood pressure and meals appear in the file twice, once on their own and again grouped. The grouped copies are not counted again.

What stays on your computer

The export is years of heart rate, sleep, weight and, for many people, cycle tracking, plus the date of birth, sex and blood type set in Health. VITALS reads it in this tab. The zip is unpacked by the browser as it is read, so even a file of several gigabytes is never uploaded or held in memory at once. The CSV files are written by this tab too.

The export also holds files VITALS does not read: ECG recordings, the routes of outdoor workouts, and clinical records from a health provider. Before sharing a route, TRAIL cuts your home out of a GPX file.