Critical Swim Speed (CSS) Calculator

A CSS (Critical Swim Speed) test helps you determine the speed you can maintain over a longer distance without burning out. This test involves swimming two timed distances, such as 400m and 200m, at your best effort. Regularly performing a CSS test is a great way to track improvements in your swimming endurance and pacing.

Select Pacing Units: Select Swim Distance Type: Enter 400m (or 400y) Swim Test Time (minutes:seconds):

Enter 200m (or 200y) Swim Test Time (minutes:seconds):