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FTP Calculator — Power Zones by Coggan

Enter your FTP (Functional Threshold Power) and get all 7 training zones by Coggan. Zones are the foundation of any wattage-based plan — from recovery to VO2max.

Zone Calculation

Coggan zones are the standard in Intervals.icu, TrainingPeaks, WKO. Each zone is a range of % FTP with a clear physiological role.

Typically 150-350W for amateurs, 350-450W for advanced

Your Zones

Z1Z1 — Active Recovery<138W
<55%Active recovery. Easy riding, warm-up, cool-down, breaks between intervals.
Z2Z2 — Endurance140–188W
56–75%Base. 80% of amateur training lives here. Rideable for hours, conversational.
Z3Z3 — Tempo190–225W
76–90%Sweet Spot and below. Steady tempo for 1-2 hours. Primary zone for SST work.
Z4Z4 — Threshold228–263W
91–105%Lactate threshold. 20-60 minutes total interval work. Key to growing FTP.
Z5Z5 — VO2max265–300W
106–120%Aerobic power. 3-8 minute intervals. Explosive fitness gains in 4-6 weeks of consistent work.
Z6Z6 — Anaerobic303–375W
121–150%Anaerobic capacity. 30 sec — 2 minute intervals. For crits, surges, attacks.
Z7Z7 — Neuromuscular>378W
>150%Sprints. 5-15 seconds at max. Neuromuscular power, peak wattage work.

How to Determine FTP

FTP is the highest power you can hold for approximately 1 hour. Testing an hour directly is brutal and rarely needed. Three practical methods:

20-minute test

Warm up 15-20 min, 20 minutes all-out (steady, not sprint), cool down. Average power × 0.95 = FTP. The classic — reliable.

Ramp test

Stepped rising power (+15-25W per minute) until failure. Final minute × 0.75 = FTP. Faster (15-25 min) but overestimates for sprinters.

Auto FTP in Intervals.icu

Intervals.icu finds your best 20-minute efforts in real workouts and recalculates FTP. Convenient — no separate test needed if you ride intensely.

When to Retest

Every 4-6 weeks during an active phase — standard. After a winter break — required. If workout TSS starts looking inflated (rides feel "heavier" than they are) — FTP has probably grown, time to retest.

FAQ

Why Coggan, not Friel?

The Coggan system is the standard in Intervals.icu, TrainingPeaks, and Zwift. Friel uses 7 zones with slightly different boundaries and anchors on LTHR, not FTP. For power training, Coggan is simpler and more universal.

Do these zones work on trainer and outdoors?

Yes — watts don't depend on terrain or surface. An SST interval at 85-88% FTP is the same on Zwift, on the road, or on gravel.

What if I only have an HR strap, no power?

Then use HR zones, not power. LTHR is measured (20-minute run or bike test) and zones are built from it. Power zones are more precise, but HR zones work.

How does FTP change with age and weight?

FTP drops with detraining (after a break) and grows with Z4-Z5 work. Weight matters for W/kg — the key number for hilly races and triathlons. 250W FTP at 70 kg and 85 kg are very different capabilities.

What is Sweet Spot?

Sweet Spot is 88-94% FTP, the top of Z3 and bottom of Z4. The point of maximum training effect at minimum fatigue. SST 2×20 is one of the most popular amateur cycling workouts.

Where do I enter FTP in Intervals.icu?

Settings → Power → FTP. Immediately after saving, workouts in the recent window get recalculated: new TSS, IF, and zones.

Related

Intervals.icu for cycling — full setup

AI cycling coach in ChatGPT and Claude

VDOT calculator — the running equivalent for pace zones

Zones in Watts → AI Plan in Watts

You have FTP and zones — let AI use them. STAS feeds Intervals.icu data to ChatGPT and Claude, AI writes a plan against your FTP.

Connect Intervals.icu

Free — no subscription

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