SWOLF in Swimming: What It Is and How to Use It

SWOLF is the number of seconds plus the number of strokes you take to swim one pool length. Lower is better, and it is only meaningful against your own earlier scores. Here is how to work it out, what changes it, and how to use it without fooling yourself.

What SWOLF is

The name joins "swimming" and "golf": as in golf, a lower score is better. Garmin's manual defines it as the sum of the time for one pool length and the number of strokes for that length. Polar calls it an indirect measure of efficiency.

The idea is simple. You can swim faster by taking more strokes, or take fewer strokes by gliding and going slowly. SWOLF puts both in one number, so it improves when the sum drops: for example the same time with fewer strokes, or a faster time with the same strokes.

How to calculate it

SWOLF = seconds for one length + strokes for that length.

Polar gives this example: 30 seconds and 10 strokes for a length make a SWOLF of 40. Garmin's is 30 seconds plus 15 strokes, which makes 45. What counts as a stroke depends on the device: Garmin's manual says a stroke is counted every time the arm wearing the watch completes a full cycle. That is one count per cycle of one arm, so counting every hand entry by hand gives a higher number for the same length.

A worked example in a 25 m pool, with made-up numbers:

• Length 1: 32 seconds and 18 strokes, SWOLF 50
• Length 2: 33 seconds and 17 strokes, SWOLF 50
• Length 3: 34 seconds and 17 strokes, SWOLF 51
• Average: 50.3

Garmin and Polar watches calculate it for you and show a score per length. If you count by hand, use a pool clock and pick one way of counting strokes, for example every time your right hand enters the water, and keep it every time.

Why the pool length changes it

SWOLF is counted per length, so the same swimmer gets a different number in a different pool. Polar's manual says to choose the correct pool length because it affects your pace, distance and stroke calculation, as well as your SWOLF score.

As an illustration (our arithmetic, not a measured figure): a swimmer who scores 50 over a 25 m length would take roughly twice the seconds and strokes over a 50 m length, and land near 100. That is not a worse swimmer, just a longer length.

So keep these apart:

• Compare 25 m scores with 25 m scores.
• Compare 50 m scores with 50 m scores.
• Never compare a 33 m pool with either. If you train in one, see how to adapt to 25, 33 or 50 m pools.

In open water, Garmin's manual says SWOLF is calculated over 25 meters.

Why it compares you only with yourself

Polar states that SWOLF is highly individual and should not be compared with scores other people have swum. People differ in build, arm length and skill, and the way strokes are counted can differ too, so a friend's number tells you little about yours.

Add one practical point. Different devices may count strokes differently, as the definition above shows. So use the same watch, the same stroke and the same pool every time.

How to use it in training

1. Pick one stroke and one pool. Freestyle in your usual pool is the easiest start.
2. Use the same short set each time. For example 4 x 50 m at a steady pace, and average the per-length scores. Start every rep the same way, from the wall or a dive, so scores stay comparable.
3. Hold the same pace and cut strokes. At a steady pace, try to lose one stroke per length through a longer reach and a better push-off. If your time stays the same, SWOLF drops.
4. Watch the trade-off. You can take fewer strokes by gliding, but then the time goes up. The sum tells you whether the change helped.
5. Track the trend, not one length. Look at the average over a set, and at how it moves over weeks. Polar says the score lets you keep track of your development.

Limits

SWOLF is a rough guide, not a verdict on your technique. Polar ties the score to a certain distance and style, so a freestyle number and a backstroke number are not the same thing. It also moves with your effort, because time is one of the two numbers in the sum: a hard length and an easy length give different scores. Polar calls it an indirect measure. Use it as a personal tool to fine-tune your technique, not as a score to chase.

If you want a pace to hold in the first place, see critical swim speed and test it in the same pool.

A plan that adapts

SwimSensei builds a plan from your level and the days you train, and adapts it every week. See how it works on the swimmers page and ask for early access.