Rolling Resistance Calculator

Rolling resistance is the force that opposes motion when a wheel, tire, or other round body rolls across a surface. Unlike aerodynamic drag, it is present even at very low speed. The resistance comes from repeated deformation of the tire and road, internal hysteresis in rubber, bearing losses, and small changes in the contact patch. A dimensionless rolling resistance coefficient, commonly written Crr, summarizes those effects for a selected tire, surface, pressure, load, and operating condition. The calculator uses the standard engineering approximation force equals Crr multiplied by the normal force. On level ground the normal force is mass multiplied by gravitational acceleration, so rolling resistance force equals Crr times mass times gravity. The answer is expressed in newtons. Power is the rate of work needed to overcome that force at a steady speed, calculated by multiplying force in newtons by velocity in meters per second. The result is watts because one watt equals one newton meter per second. Typical coefficients vary substantially. A well-inflated bicycle tire on smooth pavement may be near 0.003 to 0.006. Passenger-car tires on asphalt are often near 0.008 to 0.015, while soft ground, gravel, underinflation, or heavily deformable tires can raise the coefficient sharply. Published values are useful for preliminary analysis, but measured coast-down data is better when efficiency, race performance, battery range, or drivetrain sizing depends on the answer. The model assumes level travel, constant coefficient, and steady velocity. It does not include aerodynamic drag, slope force, acceleration, wheel-bearing friction modeled separately, transmission loss, or accessory loads. At highway speed aerodynamic power can exceed rolling power because aerodynamic force grows approximately with speed squared. For a complete vehicle requirement, add aerodynamic drag and grade forces before multiplying the combined tractive force by speed, then account for drivetrain efficiency. Use total moving mass, including passengers and cargo, rather than curb mass alone. Keep all inputs in the displayed SI units, and choose a coefficient that represents the actual tire pressure and surface. Gravity defaults to 9.81 meters per second squared for Earth but remains editable for educational or off-world calculations. The resulting force helps compare tires and surfaces, while the power result makes the energy cost at a chosen speed immediately clear.