FTP Test (20 min) — Free Zwift Workout
(.zwo Download)
Structured warm-up with two primer efforts, then a single all-out 20-minute effort. Your average watts x 0.95 is your FTP — the anchor every other workout depends on.
Built by Jim Camut. JB Cycling Academy 2004–09 · PCS-verified · Cyclingnews diarist alumnus.
Where are you in your riding?
Trains consistently — doesn't race
What do you want from this workout?
20-minute all-out — sets every other zone
How long do you have?
Live preview
Pick your settings
Free .zwo file. Drop it in your Zwift workouts folder — it shows up under Custom Workouts the next time you launch the app.
Or build your own custom workout →
FTP Test (20 min): prescription + science
A structured 20-minute test, times 0.95, gives you the FTP every other workout is built on. Here's how accurate that number really is — and how to get a clean one.
Why 95% of 20 minutes
FTP approximates the highest power you could hold for about an hour [1]. A 20-minute all-out effort is far more repeatable than a true hour test, so the 0.95 multiplier estimates that hour-power from the shorter effort.
How accurate is it
Measured against the lab gold standard — maximal lactate steady state — the 20-minute FTP test is a useful field approximation, but it tends to land slightly above MLSS and varies between riders [2, 3, 4]. Treat your number as a well-anchored estimate, not an exact physiological constant.
Getting a clean test
Warm up properly with a couple of primer efforts, pace the first few minutes conservatively, and test rested. The generator's warm-up and primers are built in — your job is an honest, even effort.
Peer-reviewed sources
- 01Borszcz et al. 2018. Functional Threshold Power in Cyclists: Validity of the Concept and Physiological Responses. International Journal of Sports Medicine, 2018.
- 02Borszcz et al. 2019. Is Functional Threshold Power Interchangeable With the Maximal Lactate Steady State in Trained Cyclists?. International Journal of Sports Physiology and Performance, 2019.
- 03Inglis et al. 2020. Maximal Lactate Steady State Versus the 20-Minute Functional Threshold Power Test in Well-Trained Individuals. International Journal of Sports Physiology and Performance, 2020.
- 04Lillo-Beviá et al. 2022. Is the Functional Threshold Power a Valid Metric to Estimate the Maximal Lactate Steady State in Cyclists?. Journal of Strength and Conditioning Research, 2022.
FTP Test (20 min): common questions
How accurate is the 20-minute FTP test?
It's a solid field estimate of your ~1-hour power, but it tends to read slightly high versus the lab's maximal-lactate-steady-state and varies between riders. Use it as a consistent anchor and retest the same way each time.
Why multiply 20-minute power by 0.95?
FTP targets roughly hour-long power, and you can hold more for 20 minutes than for 60 — so the 5% haircut estimates the longer effort.
20-minute test vs ramp test?
The 20-minute test is closer to the definition of threshold but hurts more; the ramp is easier to execute but can over- or under-estimate depending on your rider type. Pick one and stick with it for comparable numbers.
How often should I test FTP?
Every 6–8 weeks of focused training, or when your easy rides start feeling too easy. Testing more often just adds hard days without new information.
Go deeper
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