The Metric of the Pool
In swimming, your pace is strictly defined as the time it takes you to swim exactly 100 meters (or 100 yards, depending on the pool). Because water is nearly 800 times denser than air, swimming relies heavily on technique rather than sheer muscular force. Understanding your baseline 100m pace is the fundamental starting point for any structured swim training program.
Calculating Your Split
To find your true aerobic pace, you should never use a flat, all-out 100m sprint. Instead, you need to swim a longer, sustained distance (like 1500m) and calculate the average split time across the entire distance.
The Formula
The calculation translates your total time into pure seconds, divides it by the total distance to find your speed per meter, and multiplies by 100:
Pace per 100 = (Total Seconds / Total Distance) * 100
Analyzing the Result
If your calculator shows a pace of 1:45 per 100m, this is your baseline. During interval training, a coach might tell you to swim 10 sets of 100m at your baseline pace minus 5 seconds (1:40/100m). If you don't know your baseline, interval training is entirely guesswork and often leads to massive overexertion in the first few sets.