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Power = Gravity + Rolling + Drag

Watts from speed, weight, grade, wind. FTP from 20-min test. Watts/kg and zones.

Concept Fundamentals
Force × Velocity
Power (W)
Watts output
Functional threshold
FTP
1-hour max power
Power-to-weight ratio
W/kg
Climbing metric
Training zones
Application
Performance tracking
Try the Cycling Power CalculatorUse the tools below to explore something different

✨ The Fun Behind This

Why It's Fun

Power meters measure force × velocity. On the road, power = gravity + rolling resistance + aerodynamic drag.

How It Works

P_gravity = m·g·sin(grade)·v. P_rolling = Crr·m·g·cos(grade)·v. P_drag = ½·CdA·ρ·v³.

Key Insights

  • ●Pro climbers often sustain 6+ W/kg for 20+ minutes.
  • ●FTP is typically 95% of 20-minute max power.
  • ●CdA of 0.2–0.25 m² is common for time trial positions.
Sources:TrainingPeaks
🚴
SPORTSFeb 16, 2026

Cycling Power Calculator — Watts & FTP

Power from speed, weight, grade, wind. Or FTP from 20-min test. Watts/kg and zone recommendations.

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🚴 Quick Examples — Click to Load

Inputs

power_output.txtCALCULATED
# Cycling power
Power: 177 W
Watts/kg: 2.08
# FTP zone recommendations (% of FTP)
Recovery:0-55% = 0-92 W
Endurance:56-75% = 94-126 W
Tempo:76-90% = 127-151 W
Threshold:91-105% = 153-176 W
VO2 Max:106-120% = 178-201 W
Anaerobic:121-150% = 203-252 W
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Power Zone Ranges

📐 Calculation Steps

P_gravity
0 W
m*g*\text{sin}( ext{grade})*v
P_rolling
35 W
ext{Crr}*m*g*\text{cos}( ext{grade})*v
P_drag
142 W
0.5* ext{CdA}* ext{rho}*v^3
Total power
177 W
P_gravity + P_rolling + P_drag
Watts/kg
2.08
Power / 85 kg

For educational and informational purposes only. Verify with a qualified professional.

🎲 Fun Facts

6+

Pro climbers often sustain 6+ W/kg for 20+ minutes.

— Cycling

95%

FTP is typically 95% of 20-minute max power.

— Training

CdA

CdA of 0.2–0.25 m² is common for time trial positions.

— Aero

📋 Key Takeaways

  • • Power = force × velocity. On a bike: gravity (climbing), rolling resistance, and aerodynamic drag
  • • Watts/kg is the key metric for climbing; flat speed depends more on absolute watts and CdA
  • • FTP (Functional Threshold Power) ≈ 95% of your best 20-minute power
  • • CdA (drag area) varies: 0.4–0.5 upright, 0.32–0.35 TT, 0.25–0.28 pro TT
  • • Headwind adds effective speed; tailwind reduces it. Enter negative for headwind

💡 Did You Know?

⚡Power scales with the cube of speed — doubling speed requires ~8× the power (drag-dominated)Source: Physics
📐Watts/kg matters most on climbs. On flat terrain, absolute watts and CdA dominateSource: Cycling Science
🏔️A 5% climb at 15 km/h for 80 kg rider typically needs ~250–350 WSource: Climbing
🌬️10 km/h headwind can add 20–40 W at 30 km/h — significant on long ridesSource: Wind
🎯FTP zones (Recovery, Endurance, Tempo, Threshold, VO2, Anaerobic) guide training intensitySource: Training
🚴Pro TT riders have CdA around 0.25–0.28; recreational riders often 0.4–0.5Source: Aerodynamics

📖 How Cycling Power Works

Total power = P_gravity + P_rolling + P_drag. P_gravity = m·g·sin(grade)·v. P_rolling = Crr·m·g·cos(grade)·v. P_drag = ½·CdA·ρ·v³. FTP ≈ 0.95 × 20-min power.

🎯 Expert Tips

Tune CdA

Lower CdA = less power for same speed. TT bars, aero helmet, tight kit can drop CdA 10–20%.

Wind Convention

Negative wind = headwind (increases power). Positive = tailwind. Units: km/h.

Crr Values

Road: 0.004–0.006. MTB: 0.01+. Tubular: lower. Affects power at all speeds.

Watts/kg Benchmarks

Recreational: 2–2.5. Amateur: 3–4. Pro: 5.5–6.5+. Duration matters.

⚖️ Power Zone Comparison

Zone% FTP
Recovery0-55%
Endurance56-75%
Tempo76-90%
Threshold91-105%
VO2 Max106-120%
Anaerobic121-150%

❓ FAQ

What is FTP?

Functional Threshold Power — the highest power you can sustain for ~1 hour. Often estimated as 95% of 20-min max power.

What is a good watts/kg?

Recreational: 2–2.5. Competitive amateur: 3–4. Pro: 5.5–6.5+.

What is CdA?

Coefficient of drag × frontal area. Road: ~0.4–0.5. Time trial: ~0.28–0.35.

How does wind affect power?

Headwind increases power. Enter negative km/h for headwind.

What is Crr?

Coefficient of rolling resistance. Road: 0.004–0.006. MTB: 0.01+.

Can I use for indoor training?

Yes. Set wind to 0. Trainer resistance may differ from road.

Why 95% for FTP?

20-min power is slightly above 1-hour sustainable. 95% is a widely used conversion.

📊 Typical Power Stats

~200 W
Recreational steady
~250 W
Club rider tempo
~350 W
Amateur threshold
~400+ W
Pro threshold

⚠️ Disclaimer: Power estimates are approximate. Use a power meter for accurate training data.

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