Splits
Once you’ve placed markers on a race, SwimLab calculates split times automatically. The splits table appears below the video player and updates in real time as you add or adjust markers.
The Splits Table
The splits table shows a row for each segment of the race. A segment is the time between two consecutive markers.
Example for a 100m freestyle (2 laps):
| Segment | Start time | End time | Split |
|---|---|---|---|
| Reaction | 00:00.00 | 00:00.62 | 0.62s |
| Start → Turn 1 | 00:00.62 | 00:27.84 | 27.22s |
| Turn 1 → Finish | 00:27.84 | 00:56.11 | 28.27s |
| Total | 55.49s |
Which Markers Drive Splits?
| Marker pair | What it measures |
|---|---|
| Start → next Turn or Finish | First lap time |
| Turn → next Turn or Finish | Subsequent lap times |
| Reaction → Start | Reaction time |
| Turn → Breakout | Turn cycle time (wall to surface) |
| Start or Turn → 15m marker | Underwater distance / time |
Reaction Time
If you place a Reaction marker (at the starter’s signal) before the Start marker (feet leave the block), SwimLab calculates and displays reaction time separately from the first lap.
Reaction time is only as accurate as the video frame rate allows. At 60fps, precision is ±0.017s. At 30fps, precision is ±0.033s.
Underwater Metrics
If you add a 15m (Underwater) marker after a turn or start, the splits table gains extra columns:
- Underwater time — from Start/Turn to the 15m marker
- Underwater distance — always 15m (the marker location), but the time tells you how fast
- Turn cycle — from Turn to Breakout (time spent underwater and in the first stroke)
Stroke Count and Stroke Rate
SwimLab does not count strokes automatically. However, you can place Custom markers on each stroke to count manually. The splits table will show a custom row for each custom segment.
Exporting Splits
Click Export → Download splits as CSV to get a spreadsheet containing:
- All segment names and times
- Reaction time (if recorded)
- Underwater metrics (if 15m markers present)
- Date, athlete, event, and pool length
The CSV opens directly in Excel, Numbers, or Google Sheets.
Accuracy Tips
- Use 60fps footage when possible — each frame is 16ms vs. 33ms at 30fps
- Step frame-by-frame using the arrow keys when placing markers
- For turn touches in long-course races, zoom in using your browser’s zoom (Cmd + on Mac) to see the touch moment more clearly
- Backstroke turns are tricky — the touch is often below the surface; look for the underwater camera angle if available
For a full breakdown of how each number is derived: Calculations Explained →