SWOLF or "Swim Golf" is a score obtained by adding together strokes per length and the time for the length. It is often used as a measure of your swimming efficiency.
e.g. 25 meter swim at 30 seconds in 21 strokes is a SWOLF score of 51.
The core idea of SWOLF is that the fewer strokes and less time you take, the more efficient your are in the pool.
You can view your SWOLF score by clicking on the + icon on the top right corner of your swim plot. It will be added as a line bar on your plot using the Y axis on the right of the plot.
