⚡ Cycling Power Zones Calculator

How to Use This FTP Zone Calculator

FTP, functional threshold power, is the highest wattage you can hold for about an hour. Every structured cycling workout is written as a percentage of it. Enter your FTP from a recent 20-minute test or your head unit's estimate, add your weight for watts-per-kilo context, and the calculator lays out all seven Coggan zones.

The Coggan Seven-Zone Model

Andrew Coggan's model divides effort by physiological system, which is why the zones have names like "lactate threshold" instead of just numbers. Zone 2 builds the aerobic engine cheaply. Zone 4 sits at the highest sustainable intensity. Zones 5 and 6 target the systems that fail first in races. Each zone boundary is a percentage of FTP multiplied out: at 250 watts FTP, Zone 4 is 0.91x250 = 228 to 1.05x250 = 263 watts. The model assumes a fresh, well-rested test; an FTP set while fatigued understates every zone and makes workouts too easy.

Worked Example: 250 W FTP

Enter 250 watts and 75 kg. Watts per kilo = 250 / 75 = 3.33, a solid trained-amateur figure. Zone 1: 0 to 0.55x250 = 138 W. Zone 2: 0.56x250 = 140 to 0.75x250 = 188 W. Zone 3: 190 to 225 W. Zone 4: 228 to 263 W. Zone 5: 265 to 300 W. Zone 6: 303 to 375 W. Zone 7: above 375 W. Verify a few by hand: 250 x 0.76 = 190, 250 x 1.2 = 300. The calculator rounds to whole watts, which is all the precision a head unit needs.

Training With Power Zones

Most training time belongs in Zone 2: long, conversational rides that build aerobic capacity with little fatigue. One or two weekly sessions touch the higher zones: threshold intervals in Zone 4 (like 2x20 minutes), VO2 intervals in Zone 5 (like 5x4 minutes), and occasional sprints in Zone 7. Zone 1 is for recovery spins, genuinely easy. The classic mistake is living in Zone 3: hard enough to fatigue you, easy enough to do daily, and mediocre at building either base or top end. Power zones also expose fitness changes fast: when Zone 4 intervals start feeling like Zone 3, your FTP has risen and it is time to retest.

Finding Your FTP

The standard field test: after a good warm-up, ride as hard as you can sustain for 20 minutes and take 95 percent of the average power. Ramp tests, where power rises every minute until failure, give a similar number with less pacing skill required. Many head units auto-detect FTP from hard rides. Whichever method you use, test rested, on the same setup, in similar conditions. Indoor and outdoor FTP often differ by 5 to 10 percent because of cooling and motivation, so keep separate numbers if you train both ways.

Second worked example: 180 W FTP, 65 kg rider

Enter 180 watts and 65 kg. Watts per kilo = 180 / 65 = 2.77, a typical newer-rider figure. Zone 1: 0 to 0.55x180 = 99 W. Zone 2: 0.56x180 = 101 to 0.75x180 = 135 W. Zone 3: 137 to 162 W. Zone 4: 0.91x180 = 164 to 1.05x180 = 189 W. Zone 5: 191 to 216 W. Zone 6: 218 to 270 W. Zone 7: above 270 W. Verify a few by hand: 180 x 0.76 = 136.8, which rounds to 137, the Zone 3 floor. The calculator rounds to whole watts, which is all the precision a head unit needs.

Compare with the 250 W example: every zone boundary here sits 70 watts lower, but the percentages are identical. That is the point of zones: a 180 W rider doing 150 W intervals and a 250 W rider doing 208 W intervals are both in Zone 3, doing the same physiological work relative to their fitness. Never compare raw watts across riders; compare watts per kilo or zone compliance.

Power zones vs heart rate zones

Power and heart rate zones describe the same workout in different languages. Power is instant and honest: 200 watts is 200 watts regardless of heat, caffeine, or fatigue. Heart rate lags 30 to 60 seconds behind effort changes and drifts upward during long rides as you dehydrate, a phenomenon called cardiac drift. For intervals under 5 minutes, power wins clearly: heart rate barely responds before the interval ends. For long endurance rides, heart rate adds useful context: if Zone 2 power starts producing Zone 3 heart rate, you are fatigued or overheating, and that information is worth having.

The practical setup is both: program power zones as the primary target on your head unit and display heart rate alongside. When they agree, training is on track. When power says Zone 2 and heart rate says Zone 4, believe the heart rate and go easier: the body is telling you something the power meter cannot. Riders with only a heart rate monitor can still train well; they just need longer intervals where the lag matters less.

Common zone mistakes

Mistake one is a stale FTP. Fitness changes, and zones built on a spring test lie to you all summer. Retest every 6 to 8 weeks, or let your head unit auto-detect and accept its updates. Mistake two is mixing zone systems: Coggan's seven zones, Friel's zones, and polarized three-zone models all use the word "Zone 2" to mean different things. Pick one system, learn its definitions, and never compare zone numbers across systems.

Mistake three is testing indoors and training outdoors, or the reverse, without separate numbers. Cooling, motivation, and bike fit differ enough that FTP often runs 5 to 10 percent lower indoors. Keep two profiles if you split time between the trainer and the road, or your indoor Zone 4 workouts will quietly become Zone 5.

For informational purposes only, not medical advice. Consult a healthcare professional.

Zone 2: Why Everyone Argues About It

Zone 2, 56 to 75 percent of FTP, is the most debated zone in cycling because it feels too easy to matter. It matters enormously: this is where your body builds the aerobic base, improving fat burning and mitochondrial density, and professional riders spend roughly 80 percent of their training time here in polarized plans. The catch is discipline. Zone 2 only works if you stay in it, and most amateurs drift into Zone 3, which feels productive but delivers neither base nor intensity. If your Zone 2 rides keep creeping upward, you are training in the gray zone: tired enough to need recovery, easy enough to gain little.