Free swim tool
SWOLF & Swim Efficiency Calculator
Pool length, time, and stroke count in. SWOLF, stroke rate, and distance per stroke out.
SWOLF rewards fewer strokes AND less time. But it can't tell you if those strokes actually produce propulsion.
What is SWOLF?
SWOLF is your swim efficiency score. You take the time it takes to swim one length and add the number of strokes it took you to cover it. The lower the number, the more efficiently you moved through the water.
SWOLF = time (s) + stroke countThe name is a blend of swim and golf, and the logic is the same: a lower score is better. It rewards you for covering distance with both less time and fewer strokes, instead of letting you cheat one by sacrificing the other.
Stroke rate & distance per stroke
Distance per stroke is how far you travel on each pull, your pool length divided by your stroke count. A longer distance per stroke usually means a cleaner, more connected pull. Stroke rate is how many strokes you take per minute. Together they show how you produced your SWOLF: long and smooth, or short and frantic.
SWOLF FAQ
What is a good SWOLF score?
For a 25m pool, recreational swimmers often sit in the 40s, competent age-groupers in the 30s, and strong swimmers in the 20s. Yards run a few points lower because the length is shorter. The honest answer: compare your SWOLF to your own past scores, not to a chart.
How do I lower my SWOLF?
Take fewer strokes per length without slowing down, or hold the same stroke count while swimming faster. That means a longer, more connected pull, better body position, and a stroke that holds water rather than slipping through it.
What is distance per stroke?
It is how far you travel on a single stroke, your pool length divided by the strokes you took to cover it. A bigger number means each pull is moving more water and carrying you further.
Is a lower SWOLF always better?
Not always. You can game SWOLF by gliding longer to drop your stroke count, but if you glide too long you lose speed and the gain is fake. SWOLF is a useful proxy for efficiency, not the whole picture, and it can't tell you whether your strokes are actually producing propulsion.
SWOLF shows efficiency. It can't show propulsion.
SWOLF can tell you that you covered a length in fewer strokes. It can't tell you whether your hand and forearm are producing useful propulsion, or whether you simply glided more and slipped through the water. Two swimmers can post the same SWOLF with completely different engines underneath.
That is the gap ZWIM closes. A watch measures the outcome after the fact. ZWIM measures the cause: Propulsive Watts, the force your pull actually puts into the water, in real time. It doesn't replace SWOLF, and no single metric fully explains your swimming, but it trains the propulsion phase directly, between pool days, through Connected Swim Training.
Related swim tools
Track efficiency. Train the propulsion behind it.
ZWIM is Connected Swim Training for home: real Propulsive Watts and a real game, for the days you can't get to the pool.
SWOLF, stroke rate, and distance per stroke are efficiency estimates for training, not a complete measure of performance. SWOLF is a useful proxy with limits. ZWIM helps you train between pool days; it does not replace pool swimming.