Rolling Resistance Impact
Calculate rolling-resistance force, power demand, and energy loss from tire-road friction.
Last updated:
What this tool does
This calculator computes rolling-resistance force using the standard formula F = Crr × m × g, where Crr is the rolling-resistance coefficient (dimensionless), m is vehicle mass in kilograms, and g = 9.81 m/s². Primary inputs are Crr (typically 0.005–0.030), vehicle weight, speed, and distance; outputs include force in newtons, power in kilowatts, energy over the trip in kWh, and equivalent horsepower. The force calculation is independent of speed; power and energy scale linearly with velocity and distance respectively.
Compare scenarios
Continue with your figures
These calculators share inputs with this one. Change a value above and your figures travel with the link, in the part of the URL your browser never sends to a server.
Power-to-Weight Ratio Calculator
Performance & EngineeringCalculate hp/tonne and kW/tonne from horsepower and vehicle weight in seconds.
0-60 mph from Power-to-Weight
Performance & EngineeringEstimate 0–60 mph time from engine horsepower and vehicle weight using the Hales empirical formula.
Quarter Mile Time Estimator
Performance & EngineeringEstimate quarter-mile ET and trap speed from horsepower and weight using the Huntington formula.
0-100 km/h Calculator
Performance & EngineeringEstimate sprint time from power, weight and drivetrain using quarter-mile physics.
Stopping Distance (incl Reaction)
Performance & EngineeringCalculate total stopping distance including reaction time and braking distance in metres.
RPM at Given Speed Calculator
Performance & EngineeringCalculate engine RPM at any road speed from gear ratio, final drive, and tyre circumference.
How the result changes
This input can't be charted across its full range — the formula has no valid result for most of it. Pick another input above.
Export Report
How would you like to export your results?
Share
Preview
Result
—
❮ ❯ switch fields·− + change value
0
Formula
How Rolling Resistance Impact works
Rolling resistance is the force resisting motion when a tire rolls over a surface, caused by deformation of the tire and road. This calculator computes the rolling-resistance force by multiplying the coefficient of rolling resistance (Crr) by vehicle weight and gravitational acceleration (9.81 m/s²). It then scales that force by speed to show power demand in kilowatts and by trip distance to show total energy consumed overcoming tire friction. Secondary outputs convert power to horsepower and energy to kilowatt-hours.
The formula
The core equation is Frr = Crr × m × g, where Frr is rolling-resistance force in newtons, Crr is the dimensionless rolling-resistance coefficient, m is vehicle mass in kilograms, and g = 9.81 m/s². Power is then P = Frr × v (velocity in metres per second), and energy over distance d is E = Frr × d (distance in metres). The calculator converts mph to m/s (× 0.44704) and miles to metres (× 1609.344) internally.
Where this method is most accurate
The Crr × m × g model assumes constant speed on a level road, dry pavement, and properly inflated tires at operating temperature. Rolling-resistance coefficients typically range from 0.005–0.007 for low-rolling-resistance tires on smooth asphalt to 0.015–0.030 for off-road or under-inflated tires. Real-world Crr varies with tire pressure, tread design, road surface texture, and temperature; the calculation treats it as a fixed user input. Energy totals assume the entire trip occurs at the single speed entered.
What this tool does not do
This calculator does not account for aerodynamic drag, drivetrain losses, gradient, acceleration, or regenerative braking. It does not measure actual fuel economy or battery consumption—those depend on engine or motor efficiency, which varies by powertrain. The tool does not recommend tire choices, predict tread life, or certify any vehicle for a given load. Crr values must be sourced externally; the calculator performs arithmetic only on user-supplied inputs.
Disclaimer
This tool is for educational and estimation purposes only. It does not constitute vehicle-engineering advice, safety certification, or fuel-economy guarantees. Real-world rolling resistance varies with tire condition, road surface, weather, and load distribution. No calculation can replace manufacturer specifications, tyre-pressure guidelines, or professional mechanical assessment. Use outputs as indicative approximations, not as authoritative performance claims.
Questions
- What is a typical Crr value for modern passenger cars?
- Most passenger cars on standard radial tires exhibit a rolling-resistance coefficient between 0.010 and 0.015 on dry asphalt at normal operating pressure. Low-rolling-resistance or eco-focused tires may achieve 0.006–0.008, while off-road, winter, or under-inflated tires can reach 0.020 or higher. Manufacturer tire data sometimes publish Crr; otherwise coast-down testing or dynamometer measurements are required.
- Why does the force not change with speed?
- In the linear Crr model, rolling-resistance force depends only on weight and the coefficient; it is independent of velocity. Power demand, however, scales linearly with speed because power equals force times velocity. At higher speeds aerodynamic drag dominates total resistance, but rolling resistance itself remains approximately constant in this simplified framework.
- How much does tire pressure affect Crr?
- Under-inflation typically increases rolling resistance: a 20–30% drop in pressure can raise Crr by 15–25%, though the relationship is non-linear and tire-specific. Over-inflation may reduce Crr slightly but compromises contact-patch shape and ride comfort. This calculator treats Crr as a fixed input; users must adjust the coefficient manually to model pressure changes.
- Can I use this to estimate fuel or electricity consumption?
- The tool computes mechanical energy consumed by rolling resistance, not fuel or battery drain. Converting kWh to litres of fuel requires engine thermal efficiency (typically 20–35% for petrol, 30–45% for diesel); converting to battery drain requires motor efficiency (often 85–95%) and regenerative-braking recovery. Those factors vary by powertrain and are not included in the calculation.
- Does rolling resistance change on hills or curves?
- On a gradient the normal force perpendicular to the road surface decreases by cos(θ), slightly reducing rolling resistance, but the effect is small for typical road grades. Cornering can increase tire deformation and thus Crr transiently. This calculator assumes level, straight-line motion; for inclines or complex routes the force would need vector decomposition and dynamic Crr adjustment not implemented here.
Spotted something off?
Calculations or display — let us know.
Report a Problem
Help us fix issues faster
Sources & Methodology
Applies F = Crr × m × g (where g = 9.81 m/s²) to compute rolling-resistance force, then multiplies by velocity (converted from mph to m/s via × 0.44704) for power and by distance (miles × 1609.344) for energy. Based on the standard rolling-resistance model documented in SAE literature and automotive-engineering textbooks.
Related tools
Braking Distance Calculator
Calculate total stopping distance from speed, road friction and driver reaction time.
Power-to-Weight Ratio Calculator
Calculate hp/tonne and kW/tonne from horsepower and vehicle weight in seconds.
0-60 mph from Power-to-Weight
Estimate 0–60 mph time from engine horsepower and vehicle weight using the Hales empirical formula.
Quarter Mile Time Estimator
Estimate quarter-mile ET and trap speed from horsepower and weight using the Huntington formula.
Top Speed Estimator (Drag-Limited)
Calculate theoretical top speed from power, drag coefficient, and frontal area.
0-100 km/h Calculator
Estimate sprint time from power, weight and drivetrain using quarter-mile physics.
People also use
Monthly Car Payment Calculator
Financing & PurchaseCalculate your monthly car loan payment from loan amount, APR, and term in months.
Fuel Cost for a Journey
Fuel & EfficiencyCalculate the total fuel cost for a journey from distance, MPG, and fuel price per litre.
Loan vs Lease Comparison
Cost of OwnershipCompare total cost of buying on finance versus leasing over different terms and buyout scenarios.
EV vs Petrol Total Cost (5yr)
EV vs ICECompare total cost of ownership—purchase price, fuel, and depreciation—for EV vs petrol over 1–20 years.
Long Road Trip Total Cost
Practical & UtilityCalculate total fuel, lodging, food, and toll expenses for a multi-day road trip.
Depreciation % Retained Calculator
Resale & DepreciationCalculate what percentage of its original value a car has retained after depreciation.