Cycling Power Zones Calculator (FTP to Coggan zones)
Your 7 Coggan zones + Sweet Spot, in watts, bpm and W/kg. Heart rate lags, and lies in the heat. Watts do not negotiate.
The science behind the tool
The Coggan model
7 zones anchored on FTP, defined by Andrew Coggan (Training and Racing with a Power Meter). Each zone targets a distinct physiological adaptation, not a "feeling". The Sweet Spot (88 to 95 %) is the addition popularised by TrainerRoad: the best stress-to-adaptation return when training time is short.
The polarised model
3 zones bounded by your two ventilatory thresholds (Seiler). The distribution that keeps showing up in the literature on elites: ~80 % of the time in Z1, almost nothing in Z2, 15 to 20 % in Z3. If your whole volume lives in Z2 "stings a bit", you are treading water comfortably.
What are power zones
The definition
Power zones are bands of intensity, each expressed as a percentage of your FTP, each with a job. Ride in one and you are asking your body for a specific adaptation: more mitochondria and fat oxidation at the bottom, a higher sustainable power in the middle, a bigger engine and a sharper sprint at the top. The zone is the prescription; the watts are the dose.
The reference model is Andrew Coggan's, from Training and Racing with a Power Meter: seven levels, from active recovery under 55 % of FTP to neuromuscular power above 150 %. The calculator adds sweet spot at 88 to 95 %, which is not a Coggan level but a coaching convention you will meet in every plan. Everything hangs on FTP, the highest power you can hold in a quasi-steady state for about an hour. Get FTP wrong and every zone is wrong by the same margin.
How to test it
The standard shortcut is the 20 minute test, from the same book. Warm up, ride 5 minutes flat out to burn off the anaerobic reserve, recover, then ride 20 minutes as hard as you can hold evenly. FTP is 95 % of the average power of those 20 minutes. Type that number into the calculator and your zones appear.
The limit of the shortcut is the 5 %. It is an average correction for the share of the effort your anaerobic reserve paid for. A rider with a big reserve gets an FTP the model then overestimates by 10 to 15 W; a diesel gets one that undershoots. The correction does not know which you are. If you want the threshold without the guess, two maximal efforts and the critical power calculator give you CP, the physiological version of the same number, plus the size of the reserve that fooled the 20 minute test.
Three riders, one model
Three FTPs, 200, 250 and 300 W, each obtained from the 20 minute test shown in the header. The calculator on this page produced every cell.
| Level | % FTP | FTP 200 W (20 min test 211 W) | FTP 250 W (20 min test 263 W) | FTP 300 W (20 min test 316 W) |
|---|---|---|---|---|
| L1 · Active Recovery | 0 to 55 % | 0 to 110 W | 0 to 138 W | 0 to 165 W |
| L2 · Endurance | 55 to 75 % | 110 to 150 W | 138 to 188 W | 165 to 225 W |
| L3 · Tempo | 75 to 88 % | 150 to 176 W | 188 to 220 W | 225 to 264 W |
| SS · Sweet Spot | 88 to 95 % | 176 to 190 W | 220 to 238 W | 264 to 285 W |
| L4 · Threshold (FTP) | 95 to 105 % | 190 to 210 W | 238 to 263 W | 285 to 315 W |
| L5 · VO2max | 105 to 120 % | 210 to 240 W | 263 to 300 W | 315 to 360 W |
| L6 · Anaerobic Capacity | 120 to 150 % | 240 to 300 W | 300 to 375 W | 360 to 450 W |
| L7 · Neuromuscular | 150 % + | 300 W + | 375 W + | 450 W + |
The rows scale, the meaning does not. The 200 W rider's threshold interval, at 190 to 210 W, is a tempo ride for the 250 W rider and an endurance ride for the 300 W rider. Same watts, three different workouts. That is why a training plan written in watts for someone else is worth nothing to you, and one written in percentages of FTP is worth exactly as much as your FTP.
What the zones change in training
Each session gets a job. Endurance rides build the aerobic base and are wasted the moment they drift into tempo. Sweet spot and threshold raise the power you can hold. VO2max intervals raise the ceiling that threshold sits under. Anaerobic and neuromuscular work sharpens the finish. Ride a session in the wrong band and you did a different workout from the one on the plan, usually a worse one.
The week gets a shape. Where most of your hours should sit is the argument of the last decade: sweet spot for the time-poor, polarized for everyone with a podcast. What the literature actually shows, once you open the studies, is thinner than either camp admits: the sweet spot has no paper. What survives is simple: easy rides genuinely easy, hard rides genuinely hard.
Heart rate becomes a second opinion. The calculator shows heart rate next to the watts because that is the only honest way to use it: watts set the target, heart rate tells you how you are coping with it. A threshold interval at the right watts but 8 bpm above the usual heart rate is a message about heat, sleep or fatigue, not about your zones.
Where the model breaks
- The boundaries are conventions. Your body does not switch adaptation at exactly 75 % or 95 %. The real thresholds move with fatigue, heat and how long you have been riding, which is why your zones are not zones so much as neighbourhoods.
- Everything rests on one number. FTP compresses your physiology into a single value and the 20 minute test estimates that value with a fixed haircut. Two riders with the same FTP and different anaerobic reserves get the same zones and different workouts.
- Above threshold, the percentage stops meaning much. At 120 % of FTP, what limits you is how long you can stay there, and that is governed by your reserve, W', not by the percentage. For anything above level 4, the critical power model gives you a duration; the zone only gives you a label.
- Sweet spot is a coach's word. It appears in almost no cycling study. It is a sensible place to ride when your week is short; it is not a scientifically superior zone, whatever the plan you bought says.
Frequently asked questions
How do I convert FTP to power zones?
Multiply your FTP by the boundaries of each level. In Coggan's model, endurance is 55 to 75 % of FTP, tempo 75 to 88 %, threshold 95 to 105 %, VO2max 105 to 120 %. With an FTP of 250 W, threshold runs from 238 to 263 W. The calculator above does the multiplication for all seven levels plus sweet spot, in watts, W/kg and heart rate.
Can I set power zones by heart rate?
You can build heart rate zones from your lactate threshold heart rate, and the calculator shows them next to the watts. But heart rate lags 30 to 60 seconds behind the effort, drifts up with heat and dehydration, and cannot follow anything shorter than two minutes. Use it to check how you are coping with the watts, not to replace them.
How is FTP calculated from a 20 minute test?
Take the average power of a maximal, evenly paced 20 minute effort and multiply it by 0.95. A 263 W test gives an FTP of 250 W. The 5 % haircut is an average correction for the anaerobic contribution; it flatters riders with a big reserve and short-changes diesels. Two efforts and the critical power calculator get rid of that guess.
What is sweet spot, and why is it not a Coggan level?
Sweet spot is the band from 88 to 95 % of FTP, just under threshold. Coggan never defined it: it is a coaching convention popularised by training platforms, sitting across the top of tempo and the bottom of threshold. The pitch is a good adaptation return per hour when your week is short. The evidence behind that pitch is thinner than the plans suggest.
How often should I retest my FTP?
Every six to eight weeks during a build, or whenever your threshold sessions stop feeling like threshold. Zones are only as good as the number underneath them: an FTP from March makes every interval in June either too easy or too hard. Retest in the same conditions each time, same road or same trainer, rested, so the change you see is you.
What is the difference between Coggan's 7 zones and the 3-zone polarized model?
The seven levels are prescriptive: each one names a physiological target for a workout. The three polarized zones are descriptive: they sit on your two ventilatory thresholds and describe how a week is distributed, roughly 80 % easy, very little in the middle, the rest hard. The calculator shows both, because you plan a session with the first and a week with the second.
Sources
Allen H, Coggan AR (2010). Training and Racing with a Power Meter. VeloPress · 2nd edition · the seven training levels, the definition of FTP and the 20 minute test
Monod H, Scherrer J (1965). The work capacity of a synergic muscular group. Ergonomics · 8(3):329-338 · the critical power model, the physiological reading of the threshold FTP approximates · 10.1080/00140136508930810
Jones AM, Vanhatalo A, Burnley M, Morton RH, Poole DC (2010). Critical power: implications for determination of VO2max and exercise tolerance. Med Sci Sports Exerc · 42(10):1876-1890 · why the boundary between heavy and severe intensity is a real threshold, not a percentage · 10.1249/MSS.0b013e3181d9cf7f