T-pace (threshold pace) is the pace you can sustain for approximately 1,000m in a race effort, or equivalently, the pace you maintain in 10-second rest intervals at your lactate threshold. It is used to set swim training zones.

How is Critical Swim Speed (CSS) measured?

CSS = (400m time - 200m time) / 200m, expressed as seconds per 100m. It represents the fastest pace maintainable aerobically and correlates well with open water triathlon swim performance.

What training zones are based on T-pace?

Zone 1 (recovery): >T+10s/100m. Zone 2 (aerobic): T+5s. Zone 3 (threshold): T-pace. Zone 4 (VO2 pace): T-5s. Zone 5 (speed): T-10s or faster. These zones structure the bulk of structured swim training.

Swim T-Pace Threshold Pace Calculator

Calculate swim T-pace (threshold pace per 100m) from time trials to set training zones and CSS (Critical Swim Speed) for structured swim training.

Use the full interactive calculator below, or

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Frequently Asked Questions

What is swim T-pace?

How is Critical Swim Speed (CSS) measured?

What training zones are based on T-pace?