What does 'on the top' mean in swimming?

'On the top' means starting your repetition when the pace clock hand hits :00 (12 o'clock). It's the standard reference for synchronizing group sets and simplifying time and interval calculations.

How do I control intervals with the pace clock?

If your interval is 1:30 and you leave on :00, you must leave again when the hand hits :30 (after completing one full revolution + half). Your swim time + rest must fit within the interval. If you swim in 1:20, you have 10 seconds rest.

Can I use a smartwatch instead of the pace clock?

Yes, a smartwatch with interval mode serves the same function. However, learning the analog pace clock is fundamental because it's available in every pool, never needs charging, and lets you train with a group using the same time reference.

SkillsPublished on March 18, 2026· Updated on April 12, 20262 min read

How to Use the Pace Clock in Swimming

Swimer Team

International swimming coaches and high-performance technicians with 40+ years of combined experience.

Quick summary: The pace clock has a single hand completing one revolution in 60 seconds. "On the top" means leaving when the hand hits :00. Intervals are controlled by always leaving on the same number: if you leave on :00 and your interval is 1:30, your next departure is on :30 of the next minute.

The pace clock is the fundamental tool for controlling swim and rest times in every set. Using it correctly lets you train with zone-based paces and measure progress precisely.

How does the pace clock work?

Single hand (red or black) completing one revolution every 60 seconds.
Marks every 5 seconds around the dial.
No minute or hour hand — only the seconds hand.
Runs continuously — never stops or resets during the session.

Key pace clock concepts

"On the top"

Leaving when the hand hits exactly :00 (12 o'clock). It's the standard reference point. When the coach says "leave on the top," everyone leaves when the hand reaches the top.

Interval vs rest

Concept	Definition	Example
Interval	Total time from departure to next departure (swim + rest)	8×100m on 1:45 → interval = 1:45
Swim time	How long it takes to swim the distance	You swim 100m in 1:30
Rest	Interval - swim time	1:45 - 1:30 = 15 seconds rest

Practical example: 8×100m on 1:45

Assuming you leave "on the top" (:00):

Rep	Leave on	Arrive at	Next departure	Rest
1	:00	~:30 (1:30)	:45	15 sec
2	:45	~:15 (1:30)	:30	15 sec
3	:30	~:00 (1:30)	:15	15 sec
4	:15	~:45 (1:30)	:00	15 sec

Tips for beginners

Start with wide intervals: If you swim 100m in 2:00, use 2:30 interval (30 sec rest).
Mental practice: Before the set, calculate what second you should leave each rep.
Don't watch during swimming: Only look when leaving and arriving. Focusing on the clock while swimming ruins your technique.

Mastering the pace clock is essential for training with CSS zone paces. Complement with learning to take your heart rate in 10 seconds. Create your free Swimer account for automatically calculated paces.

Swimer handles all of this: connect your federated identity (RFEN, NCAA, European Aquatics) and Strava, we compute your CSS and 6 exact zones, you get adaptive cycles with automatic tapering, follow the global elite live and share PBs on the first vertical social network for swimmers. Coach Portal included. Native multi-pool. Free during launch, RFEN-backed. Join the Swimming Metaverse.

Step by step

1
Identify the clock
The pace clock has a single hand that completes one revolution in 60 seconds. Numbers from 5 to 60 mark seconds, not minutes.
2
Leave on the top (:00)
Wait for the hand to hit :00 (or :60, 12 o'clock) and start swimming. This is 'on the top' and makes calculating your time easy.
3
Read your time on arrival
When you touch the wall, look at the clock immediately. If you left on :00 and the hand reads :25, your time is 1:25 (if swimming 100m).
4
Control the interval
If your interval is 1:30, you must leave again when the hand hits :30. Your swim time + rest = interval. If you swim in 1:20, you rest 10 seconds.
5
Practice with short sets
Start with 4×50m leaving every 1:00 (on the top). When you master reading, move to more complex intervals like 1:15, 1:30, or 1:45.