Swimming Metrics

Swimming metrics help you analyze each swimming session, and follow your performance and progress in the long run.

To get the most accurate information, make sure your have set which hand you wear your watch on. You can check that you’ve set which hand you wear your watch from the product settings in Flow.

Pool swimming

When using the Swimming or Pool swimming profile, the watch identifies your swimming style and records your swim distance, time and pace, stroke rate and rest times. In addition, with the help of the SWOLF score you can keep track of your development.

Swimming Styles: Your watch recognizes the following swimming styles, and calculates style specific metrics as well as totals for your whole session:

  • Freestyle
  • Backstroke
  • Breaststroke
  • Butterfly

Pace and Distance: Once the watch has recognized your swimming style as one of the four swimming styles mentioned above, it will be able to detect your turns and use this information to give you accurate pace and distance. The pace and distance measurements are based on detected turns and the set pool length. Every time you turn, one pool length gets added to the total distance swam.

Strokes: Your watch tells you how many strokes you take in a minute or per pool length. This information can be used to find out more about your swimming technique, rhythm and timing.

SWOLF (short for swimming and golf) is an indirect measure of efficiency. SWOLF is calculated by adding together your time and the amount of strokes it takes you to swim a pool length. For instance, 30 seconds and 10 strokes to swim the length of a pool will equal a SWOLF score of 40. Generally, the lower your SWOLF is for a certain distance and style, the more efficient you are.

SWOLF is highly individual, and thus should not be compared to SWOLF scores other people have swam. It’s rather a personal tool that can help you improve and fine-tune your technique, and find an optimal efficiency for different styles.

Pool Length setting

It’s important that you choose the correct pool length, as it affects pace, distance and stroke calculation, as well as your SWOLF score. You can choose the pool length in pre-training mode from the quick menu. Press LIGHT to access the quick menu, choose the Pool length setting and change the previously set pool length if necessary. The default lengths are 25 meters, 50 meters and 25 yards, but you can also set it manually to a custom length. The minimum length that can be chosen is 20 meters/yards.

Open water swimming

When using the Open water swimming profile, the watch records your swim distance, time and pace, stroke rate for freestyle as well as your route.

Freestyle is the only style that the open water swimming profile recognizes.

Pace and Distance: Your watch uses GPS to calculate pace and distance during your swim.

Stroke rate for freestyle: Your watch records your average and maximum stroke rates (how many strokes you take per minute) for your session.

Route: Your route is recorded with GPS, and you can view it on a map after your swim in the Flow app and web service. GPS does not work underwater, and because of this your route is filtered from GPS data acquired when your hand is out of the water or very close to the water surface. External factors such as water conditions and satellite positions can affect the accuracy of the GPS data, and as a result data from the same route can vary from day to day.

Measuring heart rate in water

Your watch automatically measures your heart rate from your wrist with the new Polar Precision Prime sensor fusion technology, offering an easy and comfortable way to measure your heart rate while swimming. Although water may prevent the wrist-based heart rate measurement from working optimally, the accuracy of Polar Precision Prime is sufficient to allow you monitor your average heart rate and heart rate zones during your swimming sessions, get accurate calorie burn readings, your Training Load from the session and the Training Benefit feedback based on your heart rate zones.

To ensure the best possible accuracy of your heart rate data, it’s important to wear the watch snugly on your wrist (even more snugly than in other sports). See Training with wrist based heart rate for instructions on wearing your watch during training.

Note that you can't use a Polar heart rate sensor with a chest strap with your watch when swimming because Bluetooth doesn't work in water.

Start a swimming session

  1. Press BACK to enter the main menu, choose Start training, and then browse to the Swimming, Pool swimming or Open water swimming profile.
  2. When using the Swimming/Pool swimming profile, check that the pool length is correct. To change the pool length, press LIGHT to access the quick menu, choose Pool length setting and set the correct length.

    Do not start the training session recording until you are in the pool, however, do avoid pushing the buttons under water.

  3. Press START to begin training recording.

During your Swim

You can customize what is shown on the display in the sport profiles section in the Flow web service. The default training views in the swimming sport profiles the following information:

  • Your heart rate and the heart rate ZonePointer
  • Distance
  • Duration
  • Rest time (Swimming and Pool swimming)
  • Pace (Open water swimming)
  • Heart rate graph
  • Average heart rate
  • Maximum heart rate
  • Time of day

After your Swim

An overview of your swimming data is available in the training summary on your watch right after your session. You can see the following information:

The date and time when your session started

The duration of the session

Swimming distance

Average heart rate

Maximum heart rate

Cardio Load

Heart rate zones


Fat burn % of calories

Average pace

Maximum pace

Stroke rate (how many strokes you take per minute)

  • Average stroke rate
  • Maximum stroke rate

Sync your watch with Flow for a more detailed visual representation of your swim including a detailed breakdown of your pool swimming sessions, your heart rate, pace and stroke rate curves.