Explanation of the FastFitness Zone Calculator
Enter your best recent power (eg 233.5 watts) and corresponding time (eg 33.5 mins) for a display of your zones and the time-to-exhaustion (at mid-point of the zone)

Zone, means a band of power corresponding to a certain intensity. It is simply a short-hand for converting the continuous power-duration curve into several categories.

Whilst any zone does not correspond to any physiological variable (at least not precisely) it can be useful in training to aim for a certain power band (eg tempo) when training.

Equally useful, is to know how long in minutes each zone could be sustained for. This can be reverse calculated from the power-duration curve or in shorthand: time-to-exhaustion (TTE)

In this new take on the classic power zone model, we present each zone, linked with TTE.
In addition which also allow the entry point as any best effort, not simply FTPPlease pass on the link as https://www.cyclingapps.net/calculators/zone-calculator/  or access it as a google sheet here: https://fft.tips/zones