When you download your Fitbit history from Google Takeout you get a folder of JSON files, not the clean CSV you actually need. Wearable Converter turns those JSON files into proper CSVs ready for Garmin Connect, Excel, Google Sheets or wherever else you want them.
If you've opened your Fitbit Takeout export, you've already seen the problem. Hundreds of .json files, broken up by year and metric, hostile to anything that isn't a JavaScript console. None of it is usable as is.
This page covers two paths, depending on what you want to do with the CSVs once you have them. Both start from the same Takeout ZIP and both run in your browser, your data is never uploaded.
Pick the destination that matches what you actually want to do with the data.
You switched to a Garmin device and want your full Fitbit history imported. Output is the exact CSV format Garmin Connect requires. Garmin reads it, history fills in.
Garmin migration →You want your fitness data as clean spreadsheets, year-split CSVs and a branded Excel workbook with monthly and yearly summaries pre-built. For analysis, archive, or your own records.
Spreadsheet export →Fitbit (now Google Health) stores everything as JSON internally. When you request a Takeout export, Google gives you that raw JSON, faithfully, with no transformation. Useful for engineers, useless for everyone else.
CSV is a different format entirely. Rows and columns, one value per cell, comma-separated, opens in any spreadsheet tool. To get from one to the other you have to flatten the nested JSON structure, align dates across multiple files, convert units, handle timezone offsets, and split the data into the right rows.
This is what the converter does automatically. Drop in your ZIP, get CSVs out.
Same problem, different framings. Helpful if your specific search query isn't quite this one.