Calculate your Critical Swim Speed (CSS), your theoretical aerobic threshold pace for endurance swimming.
Time Trial Data
Test 1 (Short)
m
Test 2 (Long)
m
Ensure full recovery between the two time trial swims.
Performance Analysis
CSS Pace0:00min/100m
Threshold Speed0.00m/s
About this calculator
Critical Swim Speed
Critical Swim Speed (CSS) is an approximation of your lactate threshold speed. It's the pace you can theoretically maintain continuously without exhaustion, making it perfect for training zones.
💡
Pro Tips
Perform the 400m and 200m time trials in the same session with full recovery, or on separate days.
CSS is often slightly faster than your 1500m race pace.
Re-test every 4-8 weeks to track improvement.
!
Fun Facts
"CSS training is popularized by coaches like Paul Newsome of Swim Smooth."
"It focuses on finding a sustainable rhythm rather than pure sprint speed."
"Elite swimmers have a very small difference between their 200m and 400m paces."
