Garmin Connect's CSV importer is picky. Wrong column order, wrong date format, wrong header capitalisation, the whole upload errors out. Wearable Converter produces files in Garmin's exact required layout, year-by-year, ready to upload.
If you've tried importing Fitbit data into Garmin Connect manually, you've probably hit the wall. Garmin's importer accepts CSV files, but only in a very specific shape. The error messages don't tell you what went wrong. The documentation barely exists.
This page is about the format itself, what Garmin expects, what the common failure modes are, and how the converter handles them.
Garmin Connect's file importer accepts two distinct CSV types, with different column structures.
Activity CSV (one file per year). Columns in this exact order: Date, Steps, Distance, Calories Burned, Floors, Minutes Sedentary, Minutes Lightly Active, Minutes Fairly Active, Minutes Very Active, Activity Calories. Header row included. Dates in YYYY-MM-DD format.
Body composition CSV (one file per year). Columns: Date, Weight, BMI, Body Fat %. Same date format. Units matched to the user's Garmin Connect account preference (metric or imperial).
The converter outputs both file types, named clearly by year and category. Upload them through Garmin Connect's "Import Data" function one at a time, starting with the oldest year.
Wrong date format. Garmin's importer is sensitive to your account's regional settings. The converter outputs ISO dates (YYYY-MM-DD), which Garmin accepts as long as you select that format in the import modal. Get this wrong and the import either fails or imports dates as the wrong day entirely.
Wrong unit notation. Distance can be kilometres or miles, weight can be kilograms or pounds. The converter lets you choose at the start, then writes consistent units throughout. If your CSV mixes units, the import fails.
Opening the CSV in Excel before uploading. This is a silent killer. Excel reformats dates automatically, especially on Windows systems. After Excel touches the file, the dates often no longer match what Garmin expects. Always upload the converter output directly, don't open it in a spreadsheet first.
Importing files out of order. Garmin's servers occasionally get confused if you upload 2024 before 2023. Always go oldest to newest, one file at a time, and wait for each to fully process before starting the next.
Same problem, different framings. Helpful if your specific search query isn't quite this one.