Critical Swim Speed Calculator

Critical Swim Speed (CSS), also called lactate threshold or anaerobic threshold, is like your endurance test in swimming. It tells you how well your aerobic capacity is holding up. Plus, it's a handy predictor for how you'll fare in those longer 1500m races for example. Think of it as your pace per 100 meters or yards, giving you a solid gauge of your swim game and race strategy.

You can use this calculator to get your CSS and from there, calculate your training zones. Both in meters or yards. Now, remember, before calculating your zones you must do the Swim Fitness Test.

Done with your max 400 and 200 time trial in the same session ? then enter your times in the fields below to calculate your CSS and training zones.

Critical Swim Speed Calculator

Have you done the Swim Fitness Test ?. If yes, then enter your 400 and 200 times below.