Swim Send-Off (Interval) Calculator

1. Enter the time to swim one rep as minutes and seconds.
2. Enter the rest you want between reps, in seconds.
3. Enter the number of reps in the set.
4. Read the send-off interval and the total set time.

A send-off, also called an interval or the clock, is the time you leave on for each repeat in a swim set. It combines the time you spend swimming with the rest you take before pushing off again. A set of 10 by 100 on a send-off of 1 minute 40 means you leave every 1 minute 40 on the pace clock.

The faster you swim a rep, the more rest you get before the next send-off. Send-offs let a whole squad train together on the same clock, and they build the pacing discipline that racing demands. Learning to read the pace clock and hold your send-off is one of the first habits a squad swimmer picks up, and it quietly teaches the even pacing that pays off on race day.

1. Add your rest to your swim time for the send-off interval.
2. Round the send-off up to a tidy number on the clock if you wish.
3. Multiply the send-off by one less than the reps.
4. Add one swim time for the final rep to get the total set time.

The total uses reps minus one because you do not wait a full send-off after the last rep; the set ends when the final swim finishes.

You swim each 100 in 1 minute 25 seconds and want 15 seconds rest. The send-off is 1 minute 40 seconds. For 10 reps, the total is 1 minute 40 times nine, which is 15 minutes, plus one more swim of 1 minute 25, so about 16 minutes 25 seconds. Swim faster and you earn more rest on the same 1 minute 40 send-off, which is the built-in reward that makes send-off sets such an honest test of pacing over a long set.

Swim Speed

A faster rep on the same send-off gives more rest; a slower rep leaves less.

Rest Goal

More rest suits sprint sets; short rest builds endurance and keeps the heart rate up.

Set Purpose

Endurance sets use tight send-offs; speed sets use generous ones for full recovery.

Rounding

Send-offs are usually rounded to a clean 5 or 10 seconds so they are easy to read on the clock.

Rest earned on a fixed send-off as your swim speed changes.

This is why a send-off rewards faster swimming with more rest, and punishes fading with less.

Planning a Set

Choose a send-off that gives the rest you want at your target pace.

Timing a Session

Work out how long a set will take to fit your pool time.

Coaching a Squad

Set a shared send-off that works for the group.

1. Too Tight a Send-Off

Leaving too little rest means you cannot hold the pace and the set falls apart.

2. Odd Send-Off Numbers

Round to a clean 5 or 10 seconds so the send-off is easy to read on the clock.

3. Forgetting the Last Rep

The set ends when the final swim finishes, not a full send-off later.

4. Ignoring Fatigue

Your swim time slows through a set, so build in enough rest for the later reps.

The send-off and total maths is exact for the times you enter. It assumes a steady swim time across every rep.

It is the time you leave on for each rep of a set, combining your swim time and your rest. A 10 by 100 on 1:40 means you push off every 1 minute 40.

Add your rest to your swim time. Swimming 1:25 with 15 seconds rest gives a 1:40 send-off.

Multiply the send-off by one less than the reps, then add one swim time. Ten 100s on 1:40 with a 1:25 swim take about 16:25.

Yes. On a fixed send-off, swimming quicker leaves more rest before the next push-off, and fading leaves less.

Yes, usually to a clean 5 or 10 seconds so it is easy to read on the pace clock during the set.

A tighter send-off with short rest keeps your heart rate up. Speed sets use a longer send-off for fuller recovery.

Because you do not wait a full send-off after the last rep; the set finishes when the final swim ends.

Your swim time slows as you tire, so keep enough rest in the send-off for the harder later reps.

No. The calculator runs entirely in your browser and nothing you enter is stored or sent anywhere.

• Swimming (sport) (Wikipedia).
• Interval training (Wikipedia).
• Pace clock and training (Wikipedia).