What does SwimLapFix repair?
It reviews pool-swim length patterns in a Garmin FIT activity. The tool looks for high-confidence signs of a missed turn, represented by one unusually long length, or a false turn, represented by adjacent short fragments whose combined duration resembles a normal length. It does not repair every unusual distance and does not rewrite an activity simply because the summary differs from what you remember.
Is the detector AI?
No. The detector is deterministic. It derives a swimmer-specific baseline from active lengths in the uploaded activity and applies bounded timing rules. A long length must closely match two to four typical lengths before a split is proposed; neighboring short fragments must have a combined time that resembles one normal length before a merge is proposed. The result is repeatable for the same input and does not use a language model to guess a swimmer’s intent.
Does a proposal prove what happened?
No. An exported FIT file has recorded messages, not video or independent sensor ground truth for every wall. A long interval might be a missed turn, but it might also be a continuous swim or a rest. A short fragment might be a false turn, but it might also be intentional drill work. Preview the comparison, consider the workout context, and leave ambiguous activities unchanged.
Which files can I upload?
You can upload one Garmin FIT activity or the original ZIP export that contains it, up to 20 MB. Export the original activity from Garmin Connect rather than uploading a screenshot or a summary file. The service processes one activity at a time; do not combine unrelated FIT files into a new archive. Keep the untouched ZIP or FIT as your reference.
How do I get the original Garmin file?
In Garmin Connect on the web, open Activities, choose All Activities, open the pool swim, and use the gear menu to choose Export Original. Garmin commonly downloads a ZIP containing the FIT activity. The export and import guide has the complete checklist and duplicate-handling advice.
Why does pool size matter?
A compatible watch uses the manually selected pool size when converting detected lengths into distance. Distance is lengths multiplied by pool size, so a 25 m setting and a 25 yd setting describe different totals. Check the pool size and units before interpreting a mismatch. Correcting the setting helps future recordings but does not alter an already exported activity.
What can make a length hard for the watch to recognize?
The watch uses the accelerometer and movement around the wall. A turn or pause in stroke mechanics helps it identify a completed length, while an inconsistent cadence, a soft push-off, or a very short glide may make the transition less clear. Moving an arm during a rest can look like swimming. Garmin notes that interval/rest timing can occasionally be off by 5–10 seconds. Kick, pull, sculling, and other drills may not resemble ordinary lengths; use Garmin’s Drill Log when your model supports it.
What does a repaired FIT change?
For a high-confidence operation, the repair keeps aggregate time and strokes for affected lengths, rebuilds relevant length, lap, and session summaries, and encodes and validates a separate FIT file. It does not modify the original upload. The public FIT profile may not carry every Garmin-private field, so compare the repaired copy with the source before importing it.
How should I review and import the result?
Read the recorded and proposed distance, active-length counts, findings, and duration chart. Keep the original ZIP. If the proposed result matches your workout, import the repaired FIT through Garmin Connect’s upload/import icon, then Import Data, Browse, and Import. Garmin Connect supports FIT uploads up to 50 MB. Garmin may treat the repaired activity as a duplicate, so verify the copy before deleting or replacing anything.
What if the activity contains drills or long rests?
Drills and long rests add context that timing alone cannot supply. A kick set may intentionally remove the arm movement that helps detect a wall, and arm movement while resting can interfere with rest classification. SwimLapFix may leave such an activity unchanged rather than force a split or merge. Add notes about the set when you report a wrong detection.
Can I report a wrong detection?
Yes. The result screen has a report form for a missed correction, an incorrect correction, a wrong lap pairing, or another issue. Provide the expected distance or active-length count and any useful lap or set details. Submission requires an explicit consent checkbox because the report retains the original activity and your feedback for debugging. You can instead keep the source private and contact kf013099+swimfix@gmail.com.
How long are temporary files available?
Analysis access and download tokens expire after 15 minutes. Temporary original and repaired objects are automatically deleted within 24 hours. A wrong-detection report is retained only after explicit consent. Do not upload an activity you are not allowed to share, and read the Privacy Policy for the service’s data practices.
Where can I learn more?
Read How SwimLapFix works for the algorithm and its limits, or use the guides for Garmin setup and file handling. Garmin’s Using the Pool Swim Activity on My Garmin Watch and Tips For Using Pool Swim Workouts on a Garmin Watch pages explain pool recording and workout behavior, while the other two references explain export and manual upload: