Zwift FTP Test - 10% or 7.5% or 5% of the 20 min average

Hi Team -

I did the Zwift FTP test this morning. No ERG was used. I held a cadence between 90-100rpm. The avg wattage during the 20 min test was 326 watts. Zwift calculated that as an FTP of 309 watts. I think I could improve on the test a bit because I started out a little too strong, but the delta is probably an additional 3-5 watts (my guess). Regardless, I was curious how I should evaluate the results, meaning is the 5% reduction a good starting point or should I take 10% (or simply split it down the middle at 7.5%)? I am pretty aerobically fit. For example, I completed a 144-mile ride with 10k ft of climbing with an NP of 185 a week ago. My best 20 min outdoors was in August at 336 watts. In terms of body type, I am 6 ft 1 inch and range between 175-180lbs. I do think I need more anaerobic development.

Would love to know your thoughts? I plan on retesting on Thursday and starting a plan on Sunday. My current target is the SST + Weights plan.


I would just take 5% off of the 326 watts. Set your FTP at 310 watts.

You did an outdoor test or peak 20 minute effort at 336 watts. Indoors I would assume a slightly lower effort. We see it all the time. Usually around 5%. You were actually better than that.

I wouldn’t retest on Thursday. Zero reason to over test just for a few watts. If you get going and workouts seem to easy or too hard then you might want to plan on, at the right time. But unless that stick with 310 watt FTP at the moment.

Another metric to look at would be your peak 60 minute norm power, especially if you have done any Zwift racing. This can give you an insight into your FTP as well.

1 Like

Got it. Thanks, Coach Jake. Really appreciate it.

1 Like