Fix your swim workout file
Did your watch miss a length, create a phantom lap, or record the wrong stroke? Upload your FIT file, make corrections, and download a fixed version.
Frequently asked questions
What is Swim Blueprint?
Swim Blueprint is a web tool that lets you correct errors in pool swim recordings. If your watch missed a length, created an extra length, or recorded the wrong stroke type, you can fix those mistakes here and export a corrected version of the FIT file.
How can I split a length into two lengths?
Click the length that you wish to split and then click the "Split length" button.
How can I merge two lengths into one?
Use ctrl+click to select the two lengths (or cmd+click on Mac), and then click the "Merge lengths" button. Note that the two lengths that you select must be immediately next to each other.
How can I change the stroke type of a length?
Click the length to select it and then use the dropdown to select the new stroke type.
Can I edit "rest" lengths?
No. Only active lengths can be edited using the Swim Blueprint FIT file editor.
Can I edit laps?
This feature is not currently supported by the Swim Blueprint FIT file editor.
Can I merge two lengths that belong to different laps?
No. Lengths can only be merged if they are immediately next to each other and belong to the same lap.
Can I use the Swim Blueprint FIT file editor on a mobile device?
The Swim Blueprint FIT file editor is optimised for desktop and laptop use only.
Which devices and file formats are supported?
Swim Blueprint works with FIT files from any pool swim activity. FIT files can be exported from your swim watch or tool, e.g. Garmin Connect, Strava, etc. The tool is optimised for pool (lap) swimming activities. Open-water swims are not supported.
What corrections can I make?
You can split a single length into two equal lengths, merge two adjacent lengths within the same lap into one, and change the stroke type on any active length. These operations cover the most common mis-detection errors produced by swim watches.
Does Swim Blueprint store my FIT files?
Swim Blueprint does not store your FIT file data, so please ensure you save your original and corrected FIT files somewhere safe.
Why does my sports watch sometimes miss or duplicate lengths?
Swim watches typically use accelerometer data to detect turns and stroke cycles. Open turns, push-offs, rest periods, and unusual stroke patterns can confuse things and result in incorrect data being recorded. This is a known limitation of wrist-based swim tracking, and Swim Blueprint exists specifically to fix the resulting data errors.
About Swim Blueprint
Swim Blueprint was built by a part-time swimmer / full-time software engineer frustrated with inaccurate swimming watch data. After one too many sessions where the watch recorded the wrong number of lengths, the obvious solution was to build a tool to fix it.
The full FIT file structure including heart rate data, timestamps, and event markers is preserved in the output.
If you find a bug or want to provide feedback or feature requests, please contact us below.