Cycling Power Zones Calculator

Frequently Asked Questions

What is the most important training zone for improving cycling fitness?

Zone 2 endurance riding is the foundation. It builds mitochondrial density, fat-burning capacity, and cardiovascular efficiency in a way that no higher zone can replicate. Polarised training research consistently shows that 80% of training time at Z2 or lower, combined with 20% at Z5+, produces better long-term results than spending most time in the moderate Z3-Z4 zone.

How many Zone 4 intervals should I do per week?

Two to three threshold sessions per week is a typical maximum for most riders. A common format is 2x20 minutes at Zone 4 with 5 minutes rest, or 3x15 minutes. More than three threshold sessions per week without adequate Z1-Z2 recovery typically leads to accumulated fatigue and declining quality within 2-3 weeks.

Should my FTP sit in Zone 4?

Yes, by definition. FTP is 100% of your threshold power, and Zone 4 straddles 91-105% of FTP. Sustaining Zone 4 for longer than 40-60 minutes indicates your FTP may be underestimated - retest if you routinely finish 20-minute Z4 blocks feeling comfortable.

Why do the zone percentages have a small gap between them?

The 1% rounding gaps between zones (for example, 75% to 76%) are cosmetic artifacts of using whole numbers. In practice, Zone 2 ends where Zone 3 begins; do not obsess over being 1-2 watts above a zone boundary. The physiological transitions are gradual, not step functions.

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This calculator provides estimates for informational purposes only. Results are based on assumptions and may not reflect actual outcomes. Consult qualified professionals in relevant fields before making important decisions based on these results.

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How This Calculator Works

Power-based training divides effort into discrete intensity bands so every workout has a clear, repeatable target. This calculator uses the Coggan seven-zone model developed by Dr Andrew Coggan and Hunter Allen, the de facto standard in TrainingPeaks, Zwift, and most coaching software. You enter a single number - your Functional Threshold Power (FTP) - and the tool returns the watt range for each of the seven zones.

Everything is anchored to a percentage of FTP, so as your fitness improves and you retest, every zone scales up automatically. The zones progress from Zone 1 active recovery through Zone 7 all-out neuromuscular sprints, each targeting a different physiological adaptation.

Zone Percentages and Targets

Each zone is a fixed percentage band of FTP. The Coggan percentages are:

Z1 - Active Recovery: ≤55% FTP - very easy spinning, promotes blood flow without stress

Z2 - Endurance: 56-75% FTP - the base-building zone; trains fat oxidation, increases mitochondrial density

Z3 - Tempo: 76-90% FTP - harder than easy, useful in moderate doses; builds aerobic capacity

Z4 - Lactate Threshold: 91-105% FTP - centred exactly on FTP; sustained 2×20 min intervals target this zone

Z5 - VO2 Max: 106-120% FTP - 3-5 minute hard repeats; increases cardiac output and VO2 max

Z6 - Anaerobic Capacity: 121-150% FTP - 30-120 second efforts; trains anaerobic energy pathways

Z7 - Neuromuscular Power: >150% FTP - maximal sprints; limited only by nervous system and muscle fibre recruitment

Worked Example

A rider with FTP = 250 W. Zone 2 endurance runs from 0.56 × 250 ≈ 140 W to 0.75 × 250 ≈ 188 W - the comfortable, conversational pace. Zone 4 threshold runs 0.91 × 250 ≈ 228 W to 1.05 × 250 ≈ 263 W, the band for sustained 2×20-minute intervals. Zone 5 VO2-max work sits at 265 to 300 W, used for punchy 3-5-minute repeats. Zone 7 begins above 1.51 × 250 ≈ 378 W - sprints where the target is simply as hard as possible for a few seconds.

Key Concepts: Training Adaptation by Zone

Each zone drives a specific physiological adaptation when accumulated in the right dose:

Z2 is the foundation of endurance. Long Z2 rides build the mitochondrial density and fat-burning infrastructure that supports all higher-intensity work.

Z4 threshold work directly raises FTP by improving lactate clearance and sustainable cardiac output.

Z5 VO2-max intervals improve the ceiling of your aerobic engine - the maximum rate at which your cardiovascular system can deliver oxygen.

Z6 anaerobic work builds the ability to repeat hard accelerations - important for criteriums, track races, and attacking climbs.

Z7 neuromuscular work develops peak sprint power and fast-twitch muscle activation.

Common Mistakes

Training Zone 2 too hard. The single most common error is letting endurance rides drift into Zone 3, which adds fatigue without the targeted base-building benefit.

Using a stale FTP. An out-of-date threshold shifts every zone, so a Zone 2 ride may actually be Zone 3 if your fitness has dropped.

Confusing average and normalised power. Variable-terrain rides should be judged on normalised power, not raw average, when comparing to zones.

Expecting steady wattage in high zones. Z5-Z7 efforts are short and the wattage naturally decays within the interval - aim for the average, not a perfectly flat line.

Treating indoor and outdoor FTP as identical - many riders test 5-10% lower on a trainer, which skews every derived zone.

Tips and FAQ

How often should I retest FTP? Every 4-8 weeks during a focused block; the zones are only as good as the FTP they are built on. What is the polarised model? Many coaches group these seven into three: easy (Z1-Z2), moderate (Z3-Z4), and hard (Z5+), then spend about 80% of time easy and 20% hard, skipping the grey-zone middle. Can I use heart-rate zones instead? You can, but power responds instantly while heart rate lags by 30-60 seconds and drifts with heat and fatigue, so power zones are far more precise for short, hard intervals. Why no upper limit on Z7? Neuromuscular power is capped only by your physiology in the moment, not a percentage - a track sprinter might hit 1,500+ W for a few seconds well beyond any tidy multiple of FTP.

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