Swim Pace Calculator (per 100)

Swim pace is time per 100 — the unit every set, send-off and pace clock in the sport is written in. Enter the distance you covered and how long it took, and the calculator returns your pace per 100 along with the speed behind it.

The formula

Pace per 100 = (total time ÷ distance) × 100

Swim 400 m in 6:40, which is 400 seconds: (400 ÷ 400) × 100 = 100 seconds, so 1:40 per 100 m, or 1.00 m/s. Swim 1,500 m in 27:30 (1,650 seconds): (1,650 ÷ 1,500) × 100 = 110 seconds, a 1:50 pace.

The arithmetic never changes. What changes, and what quietly wrecks comparisons, is the unit attached to that 100.

The yards trap

The calculator works in meters, and most American pools do not. A yard is exactly 0.9144 meters, so 100 yards is 91.44 meters — 8.56% shorter. A 1:40 per 100 yards and a 1:40 per 100 meters are not the same swim, and the difference is bigger than most people’s season-long improvement.

Two ways to keep it honest:

• Stay in one course. Time trials, threshold sets and progress checks all in the same pool, and label the pace /100 y or /100 m every single time.
• Enter true meters if you must mix. Swam 500 yards? That is 457.2 m. The pace that comes back is then genuinely per 100 meters and comparable to a meters pool.

What you cannot do is treat that arithmetic as a performance conversion. Distance is one part of the difference between courses; turns are the other, and turns do not scale. The SCY to LCM conversion page covers what actually separates the three courses, and why USA Swimming does not treat a converted time as official.

From pace to a training prescription

A pace on its own is a description. It becomes a plan once you know where it sits relative to your threshold, which is what the critical swim speed calculator produces from a 400 and a 200 time trial. Sets are then written as offsets from that reference — a few seconds per 100 slower for aerobic volume, right on it for threshold work — and the swimming training zone chart maps those offsets onto the physiology they are supposed to reach.

For open water and triathlon the same pace applies, with two caveats worth pricing in: no walls to push off, and a course you almost certainly swam longer than the advertised distance. Judge those efforts on time and effort, not on a pool pace that flatters nobody.

This content is informational and does not replace coaching or medical advice.