Swim Threshold Pace Calculator

How it is calculated

The tool takes one timed swim: distance d in metres and time t in seconds. It gives the average pace per 100 m, pace = t / (d / 100) seconds, shown as m:ss, and the average speed v = d / t in metres per second with two decimals. This is the simple average pace of that one swim, not a two-test estimate: it does not subtract a second swim as the critical-speed method does. It will be a good estimate of your threshold pace only if the swim was a steady, sustained effort at that level, such as a long continuous swim you held evenly. Distance and time must both be above zero, and time must be typed in seconds as a plain number. Any combination faster than 3.5 m/s, which no swimmer can hold, shows no result; this also catches a time typed in minutes.

Common mistakes

• Typing the time as 23:00 or 23.00. The field takes seconds as a plain number, so 23 minutes is 1380. A time typed in minutes (23 for 1,500 m) implies a speed far above 3.5 m/s and shows no result.
• Entering the distance in yards or in lengths. The field is in metres; a 25-yard length is about 22.9 m, and 60 lengths of a 25 m pool is 1,500 m, not 60.
• Using a sprint or an easy swim and calling the result threshold pace. The tool only returns the average pace of the swim you give it, so the effort of that swim decides what the number means.
• Expecting a two-swim calculation. The tool uses one distance and one time. For a 400 m and 200 m test, subtract the two distances and the two times yourself and enter the differences.
• Including rest between repeats in the time. Enter the total swimming time of continuous work only, or the pace comes out too slow.