TL;DR
- FTP 250W at 75 kg → 3.33 W/kg, trained category. The engine bands this between recreational and competitive amateur.[3]
- Coggan zones span 0 to 378+ W. Most training time goes in Zone 2 (140 to 188W) for aerobic base; quality work in Zone 4 (228 to 263W) and Zone 5 (265 to 300W).
- FTP is durable, not absolute. A 20-minute test produces ±5% noise; field FTP from a well-paced effort drifts within that range across training cycles.
Power-based training has largely replaced HR-based training for serious cyclists because power tracks effort more directly. The Coggan zones map percentages of FTP to training stimuli; the W/kg ratio compares riders across weight classes. Here is what the calculator returns for a representative recreational-to-competitive amateur rider.
The scenario
A 75 kg rider with a recent 20-minute power test of 263W, FTP estimated at 250W (95% of the 20-minute average). The rider wants the full Coggan zone breakdown and a W/kg category placement for racing planning.
What the calculator returns
Running the inputs through the Cycling Power FTP Zone Calculator:
Engine input
ftp = 250
weight_kg = 75
Engine output
ftp = 250 W
wPerKg = 3.33
wPerKgCategory = "Trained"
Coggan zones (W):
Zone 1 Active recovery 0 – 138 (<55% FTP)
Zone 2 Endurance 140 – 188 (56-75% FTP)
Zone 3 Tempo 190 – 225 (76-90% FTP)
Zone 4 Lactate Threshold 228 – 263 (91-105% FTP)
Zone 5 VO2 Max 265 – 300 (106-120% FTP)
Zone 6 Anaerobic Capacity 303 – 375 (121-150% FTP)
Zone 7 Neuromuscular 378+ (>150% FTP)Seven training zones, each with a wattage range and a typical session duration. Zone 4 (228 to 263W) is the threshold zone — race pace for a 1-hour effort. Zone 5 (265 to 300W) is VO2max work — 3 to 8 minute repeats. Zone 6 above 300W is short maximal efforts, 30 seconds to 2 minutes.
Reading the zones
Zone widths reflect the metabolic demands of each system:
Zone System dominant Typical session
─────────────────────────────────────────────────────────
Z1 ATP-PC + aerobic Recovery rides, >2 h easy
Z2 Aerobic (fat ox) Long rides, 1 to 5 h
Z3 Mixed Long tempo, 30 to 90 min
Z4 Lactate threshold 20 to 60 min steady
Z5 VO2max 3 to 8 min reps × 4 to 6
Z6 Anaerobic glycolysis 30 sec to 2 min reps
Z7 ATP-PC Sprints < 30 sec
Recommended weekly distribution (polarized):
Z1 / Z2 75 to 85% of time
Z3 / Z4 5 to 15%
Z5 / Z6 / Z7 5 to 15%Most successful endurance cyclists ride 75 to 85% of their weekly time in Zone 2 (140 to 188W for this rider), with the remaining 15 to 25% split between threshold and VO2max work[1]. The temptation to ride at Zone 3 (190 to 225W) for "fitness" is what the polarized literature calls the "junk zone" — too hard for recovery, not hard enough for adaptation.
What 3.33 W/kg means competitively
The W/kg figure is the standard cross-weight comparison for cycling because climbing performance scales directly with W/kg:
W/kg sustained 60 min Category
─────────────────────────────────────────────
< 2.5 Untrained / recreational
2.5 – 3.0 Beginner cyclist
3.0 – 4.0 Trained / Cat 4-5 racer ← this rider
4.0 – 4.5 Cat 3 / strong amateur
4.5 – 5.0 Cat 2 / very strong
5.0 – 6.0 Cat 1 / elite amateur
> 6.0 Professional level
The 3.33 W/kg figure here:
Recreational climbs : strong rider
Cat 4/5 club race : competitive
Cat 3 or higher race : back of pack
Hilly century : finish strong
Sub-3-hour-30 century : achievableClimbing power is what W/kg actually predicts. On flat ground, absolute watts and aerodynamics matter more. A 250W FTP rider produces 250W on flat terrain regardless of bodyweight; on a 6% climb, the rider's effective speed scales with W/kg. The 3.33 figure puts this rider in the strong-amateur band for hilly terrain.
Where the FTP test breaks
Pacing on the 20-minute test. A rider who goes out at 290W and fades to 240W posts an average of 263W but cannot sustain 250W (95% of average) for an hour. A rider who paces conservatively at 255W flat misses 10 to 15W of true threshold. The fix is multiple tests across 4 to 6 weeks; the highest cleanly-paced effort is closest to true FTP[2].
Power meter calibration. Different power meters disagree by 1 to 5%. A new meter on a new bike can read FTP 5 to 12W higher or lower than the prior calibration. Match the test location (smart trainer, road climb, indoor trainer) across tests for consistency.
Single test point. FTP fluctuates with training fatigue. A test in week 4 of a heavy block under-reads true threshold by 10 to 20W; a test post-recovery over-reads. Pair FTP changes with subjective wellness data and HRV when possible.
A weekly training template at FTP 250W
Translating the zones into a recreational competitive week:
Mon Off or 30 min Z1 spin
Tue Z2 endurance ride, 90 min @ 150 to 175W
Wed Z5 intervals: 5 × 4 min @ 280W / 4 min @ 130W rest
Thu Z2 endurance ride, 75 min @ 150 to 170W
Fri Z4 over-under: 3 × 12 min alternating 240W / 260W
Sat Z2 long ride, 3+ hours @ 145 to 180W
Sun Z2 recovery ride, 60 min @ 130 to 150W
Weekly time: 8 to 10 hours
Weekly TSS: ~600 to 700Two quality days (Wednesday and Friday) plus a long Z2 day on Saturday cover the polarized distribution while building threshold and VO2max simultaneously. This template suits a competitive amateur with 10 hours per week; recreational riders can drop one Z2 day and one quality day for a 5 to 6 hour week.
Cross-checking against heart rate
250W FTP corresponds to a sustained heart rate of roughly 95% of HRmax for a well-trained cyclist. The Heart Rate Zone Calculator can map the rider's HR zones in parallel; HR-based zones and power-based zones should agree within 5 to 10 bpm at the threshold anchor. Disagreement signals either device error or unusual fatigue/recovery state.
Related tools and follow-ups
- Cycling Power FTP Zone Calculator — the engine used here.
- Heart Rate Zone Calculator — HR-based parallel zones for cross-checking.
- VO2 Max Estimator — aerobic ceiling for upper-zone work.
For broader context: Zone 2 training: what the literature says, Polarized vs threshold training: 2026 systematic review, and How to improve VO2 max cover the training prescription side.
FAQ
What is 3.33 W/kg in cycling terms? Trained category. The engine bands 3.0 to 4.0 W/kg as Trained, with Cat 4 racers typically in this band. Cat 3 needs 4.0 to 4.5 W/kg, Cat 2 needs 4.5 to 5.0, and Cat 1 / pro starts above 5.0 W/kg sustained.
What are the Coggan power zones for a 250W FTP? Zone 1 active recovery 0 to 138W, Zone 2 endurance 140 to 188W, Zone 3 tempo 190 to 225W, Zone 4 threshold 228 to 263W, Zone 5 VO2max 265 to 300W, Zone 6 anaerobic 303 to 375W, Zone 7 neuromuscular above 378W.
How accurate is the 20-minute test for FTP? Within plus or minus 5% of true FTP for well-paced trained cyclists. The 20-minute average × 0.95 is the standard formula; under-pacers and over-pacers both produce errors that the formula does not correct.
References
- 1 Power Training Zones 101 — the seven-zone Coggan model (Peaks Coaching Group, after Allen & Coggan, Training and Racing with a Power Meter) — Hunter Allen Power Blog / Peaks Coaching Group (2015)
- 2 Use and validity of the 20-minute test for the estimation of functional threshold power (Borszcz et al.) — International Journal of Sports Physiology and Performance (2018)
- 3 Methodology — Cycling Power FTP Zone Calculator — AI Fit Hub