Enter the distance and time into the calculator to determine the Critical Swim Speed; this calculator can also evaluate any of the variables given the others are known.

Css (Critical Swim Speed) Formula

The following formula is used to calculate the Critical Swim Speed (CSS):

CSS = (D / T) * 100


  • CSS is the Critical Swim Speed
  • D is the distance swum in meters
  • T is the time taken to swim the distance in seconds

To calculate the Critical Swim Speed, divide the distance swum by the time taken to swim the distance. Multiply the result by 100 to convert it to meters per minute.

What is a Css (Critical Swim Speed)?

Critical Swim Speed (CSS) is a concept used in swimming training to determine the maximum speed a swimmer can maintain over a prolonged period of time without fatigue. It is often used as a benchmark for designing training programs and gauging progress. CSS is typically calculated based on the time it takes a swimmer to complete two different distances, usually 200 meters and 400 meters. The difference in speed between these two distances is used to estimate the swimmer’s lactate threshold, or the point at which lactic acid begins to accumulate in the muscles faster than it can be removed, leading to fatigue. By training at or near their CSS, swimmers can improve their endurance and overall speed.

How to Calculate Css (Critical Swim Speed)?

The following steps outline how to calculate the Critical Swim Speed (CSS).

  1. First, determine the distance swum (in meters).
  2. Next, determine the time taken to swim the distance (in seconds).
  3. Next, divide the distance by the time to calculate the swim speed (in meters per second).
  4. Finally, multiply the swim speed by 100 to convert it to centimeters per second (CSS).
  5. After inserting the variables and calculating the result, check your answer with the calculator above.

Example Problem:

Use the following variables as an example problem to test your knowledge.

distance swum (m) = 200

time taken (s) = 120