How to calibrate pool length on Fitbit devices

Make sure you're getting the most accurate swim tracking data
Lifestyle photo of Ionic Outdoor Young Adult Male
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We had to wait a while, but we finally got ourselves a waterproof Fitbit. In fact, there are now a bunch of Fitbits that can survive a dip in the pool and the sea.

The Fitbit Flex 2 was the first to get some waterproofing love, then came the Ionic and Versa smartwatches – then the Charge 3 became the first iteration of the flagship tracker to join the party.

Essential reading: Fitbit missing manual – Everything you need to know

Along with making wearing that Fitbit a truly 24/7 affair, we also got the ability to track our swimming in the water, specifically the pool. All of the devices mentioned above have the ability to do that, although what you can view on the device differs from the screen-lacking Flex 2 in comparison to the Ionic, for instance. Ultimately though, you can get that additional hit of swim data that can contribute towards your daily activity goal.

Fitbit's waterproof (and swim-proof wearables) are pretty adept at measuring swim activity based on our experience. But there are some things you can do prior to slipping on the goggles to help get reliable data – most notably, setting up the right pool length so that your Fitbit can accurately register laps and stroke counts. You don't want to hit a 50m pool with your Fitbit set up to track 25m lengths and see your data well and truly fudged.

So how do you calibrate pool length your Fitbit? Here's the quickest way to do it depending on your device.

How to calibrate pool length on Fitbit Versa and Ionic

How to calibrate pool length on Fitbit devices

The good news is that if you're swim tracking with one of Fitbit's smartwatches, it's really easy to make sure you're properly set up for swim tracking.

  • On your Versa or Ionic, open up the Exercise app and swipe to the Swim screen
  • Tap the small cog in the top corner of the screen to view swim tracking settings
  • Select Pool Length and from here you'll be able to adjust pool length

How to calibrate pool length on Fitbit Charge 3 and Charge 4

Like the Ionic and Versa, the Charge 4 does have a screen and does allow you to adjust pool length directly from the device. Here's how you do it.

  • On your Charge 4, swipe to find the Exercise mode screen and select swim
  • From there, swipe up to see your swim tracking settings where you'll be able to select the correct pool length
  • Now you're good to get swimming!

How to calibrate pool length on Fitbit Flex 2

The Fitbit Flex 2 doesn't have a proper display like the Charge 4 or Fitbit's smartwatches, which means it uses automatic exercise recognition to know when you start swimming. As a default, swim tracking is turned off too, so that means it's even more important to jump into the Fitbit app to switch swim tracking on and calibrate pool length.

How to calibrate pool length on Fitbit devices

To turn swim tracking on, do the following:

  • Go to the Fitbit app on your phone and select the Account icon
  • Next, under Goals tap Exercise. Select Swimming and tap Auto-Recognize
  • You can also adjust the amount of swimming time it takes before the Flex 2 starts registering it as an activity. You may want to have a shorter swimming time if you're not going to have a big swim session, for instance

Now, to calibrate pool length:

  • When you're ready to calibrate pool length, go back to the dashboard screen and tap the Account icon again
  • Go to Settings and then Advanced Settings
  • Tap Swim Settings and enter pool length. You can enter in either metres or yards depending on what unit of measurement you're used to.

Got any questions about the above instructions? Let us know in the comments section below.

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Michael Sawh


Michael Sawh has been covering the wearable tech industry since the very first Fitbit landed back in 2011. Previously the resident wearable tech expert at Trusted Reviews, he also marshaled the features section of

He also regularly contributed to T3 magazine when they needed someone to talk about fitness trackers, running watches, headphones, tablets, and phones.

Michael writes for GQ, Wired, Coach Mag, Metro, MSN, BBC Focus, Stuff, TechRadar and has made several appearances on the BBC Travel Show to talk all things tech. 

Michael is a lover of all things sports and fitness-tech related, clocking up over 15 marathons and has put in serious hours in the pool all in the name of testing every fitness wearable going. Expect to see him with a minimum of two wearables at any given time.

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