Cycling Wattage Calculator: Power, Speed, and W/kg

Your details

Your body weight without gear.
kg
Bicycle, helmet, shoes, water, and everything you carry.
kg
Your target or actual average speed.
km/h
Positive = uphill, negative = downhill. 5% is a moderately steep climb.
%
Positive = headwind (adds resistance), negative = tailwind (reduces it).
km/h
Higher altitude means thinner air and less aerodynamic drag.
m
Your handlebar position determines your frontal area and drag coefficient (CdA).
Drivetrain efficiency loss ranges from about 1.5% (new) to 5% (dry chain).
Power requiredUntrained
137.5W

Total watts needed to maintain your entered speed under these conditions

Power-to-weight ratio1.83W/kg
Gravity component0W
Rolling resistance20.9W
Aerodynamic drag116.6W
Drivetrain loss2.1W
Calories burned493kcal/h
Gravity0
Rolling resistance20.9
Aero drag116.6
Drivetrain loss2.1

You need 138 W to hold 30 km/h.

  • At 30 km/h, your biggest power expense is aerodynamic drag.
  • Your power-to-weight ratio of 1.83 W/kg places you in the Untrained category.
  • On flat ground in still air, improving your aerodynamic position (CdA) is the single highest-return change you can make.
  • You burn roughly 493 kcal per hour at this effort.

Next stepConsistent zone-2 riding (60-75% max heart rate) for 8-12 weeks is the best way to raise your aerobic base and W/kg.

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