That big clock in the pool is called a pace clock. It’s a tool that swimmers use when training in the pool. It’s not just for competitive swimmers but can be useful to all abilities even people swimming for triathlon or those just learning front crawl. Learning how to use the swim clock will help you to figure out how to swim faster. 

Pace clock to help you swim faster
What’s it for?

The big clock is usually found at one end of a swimming pool. It’s not used for telling time of day but is used monitor how long it takes to swim distances and repeats in the pool. 

What does it look like?

It does not have a minute and hour hand. Instead just one single sided second hand that is usually red on one end and black at the other end.

The face of the clock is marked in seconds and numbered by 5s with 60 “at the top” and 30 “at the bottom.”

It runs continuously and will hopefully be placed where it can be seen from anywhere in the pool.

Why use a pace clock?
  • To monitor your time for particular distances.
  • It helps with pacing and learning how to swim at different paces.
  • To control rest intervals (RI)
  • Monitoring what happens to your pace/speed/form as you get tired/changed pace.
  • Improved focus
  • Gives structure
  • To give rhythm and discipline to you swim sets and practices
  • Learning to correlate effort with speed, distance and pace.
  • Some swim devices have delay on pressing a lap button so using the pace clock can be more accurate
  • It doesn’t disrupt a set or group swim by playing around with a watch.
How to use a pace clock

If you are planning to swim 100metres front crawl. Look at the pace clock and start your swim leaving the wall with the red hand pointing at a particular number. It’s simplest for the red hand to be pointing to the top (eg in the 12 O’clock position).

Swim 100m and as you finish look up at the clock to see where the red hand is pointing. If it’s pointing at the top again (eg 12 o’clock position) then you’ve swam 100metres in 2 minutes (1minute would make you an Olympian and 3minutes would be for a beginner). If it’s pointing at the bottom then you’ve swam your 100metres in 2min 30.

It’s helpful to know roughly how long it will take you to swim a certain distance. So if you know it usually takes you 2minutesd and 5 seconds to swim 100m and when you stop the clock is pointing at 3 seconds past then you know you’ve taken 2min and 3 seconds.

You could then time your rest interval (RI) for 30seconds and when the red top is at the bottom you know to start your next set.

On The Red Top

Swimmers commonly refer to “on the red top”. This means we’ll start the rep with the red hand pointing to the 12 O’clock position. “On the red 5” means that you start your swim with the red hand pointing at 5 past etc.

If swimming with a group, swimmers usually leave 5 second gaps between each swimmer so remember to look to see what number you started your swim at.

It can be a bit confusing to start with but once you get the hang of using the pace clock it can bring another dimension to your swimming. Personally a good set of 20 x 100 off 2 minutes with the pace clock is a great way to start the day!

More Tips
  • For ideas on how to make your swimming sessions more interesting click here
  • To learn what other numbers are useful to know about in your swim practice click here
  • To find out about how to use a tempo trainer to swim faster click here 

How can I help?

If you want to make your swim training more effective or need to help to train for a big event email to see how I can help.

To improve your technique book a one-to-one swimming lesson here and find out when the next swimming workshops are here.

Or Book a free 15min call here to find out how I can help you reach your goals.


I’m Penny and I’m a triathlete and wild swimmer with a passion for outdoor adventures. I’m a triathlon coach and Total Immersion Swimming Teacher and I help people feel more comfortable in the water so they can swim further, discover the joy of swimming or finish a triathlon without feeling exhausted.