CSS Calculator

Calculate Critical Swim Speed with our handy calculator

Calculate your CSS

Calculate Critical Swim Speed with our handy calculator. Critical Swim Speed (CSS) is an effective tool to measure swimming speed improvement over time and predict time to complete larger distances. Critical Swim Speed is an estimate of your pace over a long distance. It's calculated by comparing your 200m time trial to your 400m time trial.

What is CSS?

Critical Swim Speed.

When we train for swimming, it's rare we swim further than 200 meters without stopping. Even at the highest level of swimming training. Because of this, it can be hard to estimate how fast we can swim comfortably over a long distance like 1500m in a triathlon. We use the Critical Swim Speed calculator to give a best estimate for how long we will be able to swim these long distances without having to actually complete them.

CSS Training

Once you know your critical swim speed, you can incorporate swimming sets which challenge this time and you can record your improvement over time. After you have done your warm up and any swimming drills, try completing 10 x 100m at a pace 15 seconds faster than your CSS, then take a 15 second rest at the wall. You can also incorporate your CSS into our Scale Swimming Waterproof books.

Get Our Waterproof Training Books

Critical Swim Speed

Test You CSS