Swim Pace Calculator

Free swim pace calculator with five tools in one: distance/time/pace solver, 100 m ↔ 100 yd pace converter, race-pace split table from 25 m to 1 mile, pool-length lap calculator, and CSS (Critical Swim Speed) threshold estimator from a 200 m + 400 m test. Works for triathletes, masters swimmers, and pool swimmers in metric or yard pools. What is swim pace?

Swim pace is almost always expressed as time per 100 of your unit — usually seconds per 100 m in metric pools or seconds per 100 yd in US-style 25 yard pools. A pace of 1:30 / 100 m means a sustained speed of about 1.11 m/s, which over a 1500 m swim works out to roughly 22:30. How do I convert between 100 m and 100 yd? One yard equals exactly 0.9144 meters, so a 100 yd interval is shorter than 100 m.

At the same speed, your 100 yd time is about 91.44% of your 100 m time. Multiply your seconds-per-100m pace by 0.9144 to get seconds-per-100yd. The pace converter does this in real time so you can compare workouts written in either unit without doing the math by hand. What is CSS pace? Critical Swim Speed is the slope between two all-out efforts at different distances.

The classic Wakayoshi formula uses 200 m and 400 m: subtract the times, divide by 200 m, and you have the speed you can hold under threshold. Triathlon and open-water coaches use CSS as a sustainable interval pace anchor — usually for 100s, 200s, 300s, and 400s on short rest. How accurate is CSS pace? CSS based on a 200 m + 400 m test gives a strong estimate of your threshold for 20-30 minute swims.

It works best when both trials are maximal, fully rested between, and swum on the same day. Race-pace splits in one glance: once you know your target pace, the split table projects how long each standard distance would take at that effort. It is the fastest way to sanity-check whether the workout you wrote down is actually swimmable — if a 400 m at goal pace blows past your realistic ceiling, the math is going to find out before the pool does.

Can I use this calculator for triathlon swim training? Yes. Triathletes commonly use the split table for race-pace prediction over 750 m, 1500 m, and 1900 m, and use CSS pace to anchor open-water threshold sets in the pool. Can I use this for open-water swim pacing? Yes, with one caveat. Pool pace is the cleanest baseline, but open water adds chop, sighting, drafting, and no wall push-offs, so most swimmers add roughly 3 to 8 seconds per 100 m in a race.

Calculate your pool pace here, then pad it for conditions when you plan an open-water effort. How do I convert between 25 m and 50 m pool pace? Pace per 100 stays the same unit either way, so the number does not change between pool lengths. What changes is your real speed: a 50 m pool has half as many turns, and every push-off is free speed, so most swimmers are 1 to 3 seconds per 100 slower in a 50 m pool than a 25 m pool at the same effort.

How is this different from the pace on my Garmin watch? Your watch reports the pace you actually swam, measured live from wrist motion and lap touches. This calculator works the other way: you give it a target, and it tells you the splits, total time, or pace you need to plan a set before you get in the water. Use the watch to record, this to prescribe.