⚡ Calculate Power Output from Speed & Terrain
km/h
Your average speed for this ride/effort
Enter speed between 1 and 120 km/h.
%
0 = flat, positive = uphill, negative = downhill
Enter rider weight 30-200 kg.
Road bike: 7-9 kg | MTB: 10-14 kg
Power Output
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⚠️ Disclaimer: Power calculations use the validated Whitt & Wilson physics equation. Actual power varies with wind speed, road surface, altitude, and drivetrain losses. Always use a calibrated power meter for precise measurements. Results are for training planning purposes only.
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Sources & Methodology
Power equation from Whitt & Wilson, the authoritative reference for cycling physics. FTP zones from Coggan (2003). All constants verified against published values.
Whitt, F.R. & Wilson, D.G. (2004). Bicycling Science, 3rd Ed. MIT Press.
The authoritative reference for cycling power physics. Source for the three-component power equation: P = P_gravity + P_rolling + P_aero. Rolling resistance coefficient (Crr = 0.004 for road tires on smooth asphalt) and air density constants (rho = 1.225 kg/m^3 at sea level, 20 degrees Celsius) used in this calculator come from this publication.
Coggan, A.R. (2003). Power Training Levels — TrainingPeaks.
Source for the 7-zone FTP training system used by TrainingPeaks, Garmin, Wahoo, and most power-based platforms. Zone percentages: Z1 under 55%, Z2 55-75%, Z3 75-90%, Z4 90-105%, Z5 105-120%, Z6 120-150%, Z7 above 150% FTP.
Cycling Power Equation (Whitt & Wilson, verified):
/* G=9.81 m/s^2, Crr=0.004 road tires, rho=1.225 kg/m^3, efficiency=0.976 */ P_gravity = totalMass x G x velocity(m/s) x gradient(decimal) P_rolling = Crr x totalMass x G x velocity(m/s) P_aero = 0.5 x CdA x rho x velocity^3 P_total = (P_gravity + P_rolling + P_aero) / 0.976 w/kg = watts / bodyMass(kg)
/* G=9.81 m/s^2, Crr=0.004 road tires, rho=1.225 kg/m^3, efficiency=0.976 */ P_gravity = totalMass x G x velocity(m/s) x gradient(decimal) P_rolling = Crr x totalMass x G x velocity(m/s) P_aero = 0.5 x CdA x rho x velocity^3 P_total = (P_gravity + P_rolling + P_aero) / 0.976 w/kg = watts / bodyMass(kg)
Last reviewed: April 2026
Cycling Wattage Calculator — Power, FTP Zones & w/kg Explained
Cycling power (watts) is the gold standard training metric in modern cycling. Unlike heart rate — which lags by 20-30 seconds and is affected by heat, caffeine, and fatigue — power responds instantaneously and measures the actual work being done. This calculator gives you three connected tools: power calculation from speed and terrain, your 7-zone FTP training system, and your watts-per-kg category.
The Three Forces Every Cyclist Overcomes
At any given speed, a cyclist must overcome gravity (on climbs), rolling resistance (always present), and aerodynamic drag (dominant at speed). The proportion of each force changes dramatically with gradient and speed:
- Flat road at 30 km/h: Aero drag ~80%, Rolling ~20%, Gravity 0%
- 5% climb at 15 km/h: Gravity ~75%, Rolling ~15%, Aero ~10%
- 10% climb at 10 km/h: Gravity ~85%, Rolling ~12%, Aero ~3%
This explains why aerodynamics dominates flat racing (why pro time trialists spend thousands on aero kit) while weight dominates climbing (why w/kg is the key metric for mountain stages).
Flat Road Power Reference Table
| Speed | 60 kg rider | 75 kg rider | 90 kg rider | Notes |
|---|---|---|---|---|
| 20 km/h | 62W | 72W | 84W | Easy pace, road drops |
| 25 km/h | 107W | 121W | 137W | Moderate pace |
| 30 km/h | 172W | 190W | 210W | Brisk training pace |
| 35 km/h | 265W | 288W | 313W | Race pace for amateurs |
| 40 km/h | 395W | 425W | 457W | Requires strong FTP |
| 45 km/h | 571W | 608W | 649W | Sprint/elite sustained |
FTP and the Coggan 7-Zone Training System
FTP (Functional Threshold Power) is the maximum average power sustainable for approximately 60 minutes. Estimate it as 95% of your best 20-minute all-out power. Andrew Coggan's 7-zone system derived from FTP is the global standard:
| Zone | Name | % FTP | Example (FTP=250W) | Primary Adaptation |
|---|---|---|---|---|
| Z1 | Active Recovery | <55% | <138W | Recovery, fatigue clearance |
| Z2 | Endurance | 55-75% | 138-188W | Aerobic base, fat oxidation |
| Z3 | Tempo | 75-90% | 188-225W | Aerobic capacity, muscular endurance |
| Z4 | Threshold (FTP) | 90-105% | 225-263W | Lactate threshold improvement |
| Z5 | VO2 Max | 105-120% | 263-300W | Aerobic ceiling development |
| Z6 | Anaerobic | 120-150% | 300-375W | Anaerobic capacity |
| Z7 | Neuromuscular | >150% | >375W | Peak sprint power |
Watts per Kilogram (w/kg) Rider Categories
| w/kg (FTP) | Category | Zwift | Real-World Context |
|---|---|---|---|
| <1.5 | Untrained | D | New to cycling, first year |
| 1.5-2.5 | Recreational | D | Casual cyclist, fitness focus |
| 2.5-3.5 | Active | C | Regular cyclist, completes sportives |
| 3.5-4.5 | Trained | B | Club rider, competitive in gran fondos |
| 4.5-5.5 | Cat 3-4 Racer | A | Competitive amateur racer |
| 5.5-6.5 | Elite Amateur | A+ | Cat 1-2, UCI continental team level |
| 6.5+ | Professional | Pro | WorldTour professional cyclist |
💡 Sweet Spot Training (88-94% FTP): The most efficient zone for FTP improvement is between Zone 3 and Zone 4, called Sweet Spot. Research shows 2-3 weekly sessions of 20-40 minutes at Sweet Spot produce larger FTP gains per training hour than any other approach. For a 250W FTP cyclist, Sweet Spot = 220-235W. This is why structured training plans center around Sweet Spot intervals in the base phase.
Frequently Asked Questions
P_total = (P_gravity + P_rolling + P_aero) / drivetrain_efficiency. P_gravity = mass x 9.81 x speed (m/s) x slope fraction. P_rolling = 0.004 x mass x 9.81 x speed. P_aero = 0.5 x CdA x 1.225 x speed cubed. Divide total by 0.976 for drivetrain losses. Use the Calculate Watts tab above with your speed, gradient, weight, and riding position for an instant result.
FTP (Functional Threshold Power) is the maximum average power sustainable for approximately 60 minutes. Estimate it as 95% of your best 20-minute all-out average power from a TT effort. Average recreational FTP: 150-250 watts. Strong amateur: 250-350 watts. Elite amateur: 350-450 watts. Professional: 400-500+ watts. Enter your FTP in the FTP Power Zones tab to generate your full 7-zone Coggan training system.
w/kg = FTP watts / body mass in kg. A 250W FTP at 70 kg = 3.57 w/kg. A 250W FTP at 80 kg = 3.13 w/kg. This metric is most important for climbing — gravity scales with mass but power does not, so heavier riders with the same w/kg climb at exactly the same speed. Tour de France climbers produce approximately 6.0-6.5 w/kg on major ascents. The w/kg tab above calculates your rating and compares it to standard rider categories.
Untrained adults: 50-150 watts sustained. Casual recreational: 100-175 watts. Trained recreational: 150-250 watts. Reference speeds for 75 kg rider on flat in drops position: 20 km/h requires ~80W, 25 km/h ~130W, 30 km/h ~175W, 40 km/h ~320W. Use the Calculate Watts tab to see exactly how much power your current average speed requires with your own weight and riding position.
Zone 1 (Active Recovery) under 55% FTP. Zone 2 (Endurance) 55-75%. Zone 3 (Tempo) 75-90%. Zone 4 (Threshold) 90-105%. Zone 5 (VO2 Max) 105-120%. Zone 6 (Anaerobic) 120-150%. Zone 7 (Neuromuscular) above 150% FTP. This is the system used by TrainingPeaks, Garmin, Wahoo, and all major platforms. Enter your FTP above to get your exact watt values for every zone.
For 75 kg rider (plus 8 kg bike) at 15 km/h: 0% grade ~65W, 3% ~165W, 5% ~255W, 8% ~385W, 10% ~465W. Gravity dominates on steep climbs (70-85% of total power), making w/kg the key metric for climbing performance. A 1 kg weight reduction saves the same power as roughly a 1.5% speed increase on a 5% grade. Use the Calculate Watts tab with different grade values to see the gradient effect on your power requirement.
CdA (drag area in m^2) measures aerodynamic resistance. Lower = faster. Upright commuter: 0.50-0.60. Road hoods: 0.38-0.42. Road drops: 0.32-0.36. Tri bars: 0.22-0.26. Pro TT: 0.18-0.20. At 40 km/h, improving CdA from 0.38 to 0.30 saves approximately 25-30 watts — equivalent to months of fitness training. Aerodynamics accounts for 80%+ of resistance on flat roads above 30 km/h, which is why pro time trialists invest heavily in position and equipment.
Methods: 1) 20-minute test: all-out TT effort for exactly 20 minutes, multiply average power by 0.95. 2) Ramp test: increase power 20W every minute until failure, FTP equals approximately 75% of peak 1-minute power. 3) Best 60-minute race or TT power approximately equals FTP. 4) Power meter software (TrainingPeaks, Garmin Connect) estimates FTP from recent ride history. The ramp test is preferred by many coaches as it is shorter and less fatiguing than a full 20-minute max effort.
Under 2.0 w/kg = beginner climber. 2.0-3.0 = recreational, can finish most sportive climbs. 3.0-4.0 = solid club rider. 4.0-5.0 = competitive amateur. 5.0-5.5 = top domestic amateur. 5.5-6.5 = professional continental team. 6.5+ = WorldTour Tour de France level. Froome and elite Tour climbers were estimated at 6.0-6.2 w/kg on Alpe d'Huez. Use the w/kg tab above to see your current category and how much power or weight change is needed for the next level.
Most effective methods: 1) Sweet Spot Training (88-94% FTP, i.e. 220-235W for 250W FTP): 2-3 sessions per week of 20-40 min. Most efficient FTP builder. 2) VO2 max intervals: 4-6 min at 110-120% FTP, 4-6 reps with equal recovery. 3) Zone 2 base volume: 10-15+ hours/week at 55-75% FTP builds mitochondrial density over months. 4) Heavy strength training: squats, deadlifts improve neuromuscular power. Most cyclists improve FTP 5-15% over 3 months of structured training.
Professional cyclists combine: VO2 max of 70-85 mL/kg/min (very high oxygen delivery), lactate threshold at 85-95% of VO2 max (sustaining hard efforts for hours), superior cycling economy (less oxygen per watt), extreme power-to-weight ratio via low body fat, and 25,000-30,000+ km training per year over 10+ years of progressive development. The combination produces w/kg ratios of 5.5-6.5+ that separate professionals from even elite amateurs.
Popular options: Pedal-based (easy to transfer between bikes): Garmin Rally, Favero Assioma, LOOK Keo Power. Crank-arm: Stages, 4iiii. Chainring: Quarq, Rotor. Price range: $300-$500 for single-sided, $700-$1,500 for dual-sided. For training and FTP tracking, any single-sided meter provides useful relative power data. Dual-sided meters additionally measure left/right balance. All connect via ANT+ or Bluetooth to cycling computers and smartphones.
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