Calculator Inputs
Example Data Table
| Case | Wheel Torque | Gear Ratio | Final Drive | Efficiency | Driven Wheels | Source Torque | Tractive Force |
|---|---|---|---|---|---|---|---|
| EV axle check | 2,400 N·m | 9.10 | 1.00 | 94% | 2 | 280.53 N·m | 6,857.14 N |
| Passenger car launch | 1,800 N·m | 3.50 | 4.10 | 90% | 2 | 139.37 N·m | 5,625.00 N |
| Truck low gear | 5,200 N·m | 6.20 | 4.88 | 88% | 2 | 195.20 N·m | 10,833.33 N |
Formula Used
Total Reduction = Gear Ratio × Final Drive Ratio
Effective Reduction = Total Reduction × Drivetrain Efficiency
Wheel Torque Total = Source Torque × Effective Reduction
Required Source Torque = Wheel Torque Total ÷ Effective Reduction
Wheel Torque Per Wheel = Wheel Torque Total ÷ Driven Wheels
Tractive Force = Wheel Torque Total ÷ Wheel Radius
Design Torque = Calculated Torque × Service Factor
This model helps convert between delivered wheel torque and upstream torque while accounting for gearing, losses, radius, and driven wheel count.
How to Use This Calculator
- Select the calculation mode.
- Choose whether wheel torque is total or per wheel.
- Enter wheel torque or source torque, based on mode.
- Pick input and output torque units.
- Enter the gear ratio and final drive ratio.
- Set drivetrain efficiency as a percentage.
- Enter driven wheels and wheel radius.
- Apply a service factor for design allowance.
- Press calculate.
- Review torque, reduction, and tractive force results.
- Use CSV or PDF export for reporting.
Wheel Torque to Torque Guide
Why this conversion matters
Wheel torque shows the turning effort available at the driven tire. It matters in launch feel, climb performance, towing response, and traction planning. Engineers often need the opposite view as well. They must estimate the upstream torque required from a motor, gearbox input, or shaft. That reverse check helps with component sizing. It also supports durability reviews and drivetrain comparisons.
What changes the answer
The biggest variables are gear ratio, final drive ratio, and drivetrain efficiency. A larger reduction multiplies torque at the wheel. Efficiency lowers the ideal value because every driveline loses energy. Bearings, gears, seals, shafts, and joints all add losses. Wheel radius changes tractive force too. The same torque creates less road force with a larger radius. Driven wheel count also changes the per-wheel split.
How engineers use the result
This calculator is useful in vehicle design, electric drive studies, gearbox checks, and race setup work. It converts wheel torque into source torque fast. It also converts source torque into wheel torque for forward analysis. That helps validate ratios before testing. Tractive force output is valuable during acceleration estimates. It also helps when matching torque targets to available grip.
Why service factor is included
Real systems rarely work in perfect conditions. Shock loads, road impacts, launch spikes, and wear can all raise demand. A service factor adds a conservative design layer. That makes the result more useful for shaft, spline, axle, and gear selection. Use measured values when possible. Then compare calculated results with test data, manufacturer limits, and traction constraints for better engineering decisions.
Frequently Asked Questions
1. What is wheel torque?
Wheel torque is the twisting effort delivered at the driven wheel. It is the torque that creates tractive force at the road surface.
2. Why is drivetrain efficiency important?
Efficiency accounts for losses through gears, bearings, seals, joints, and shafts. Ignoring it can overstate wheel torque or understate required source torque.
3. What is the difference between total and per-wheel torque?
Total torque is the combined value across all driven wheels. Per-wheel torque is the split value at one driven wheel.
4. Can I use lb-ft instead of N·m?
Yes. The calculator accepts N·m, lb-ft, and kgf·m. It also lets you choose a separate output torque unit.
5. Why does wheel radius affect force?
Force equals torque divided by radius. A larger radius reduces tractive force for the same wheel torque.
6. What does service factor do?
Service factor adds a design allowance. It helps estimate a safer torque target for engineering checks and component sizing.
7. Is this useful for electric vehicles?
Yes. It works well for electric drives, reduction gearboxes, axle checks, and traction estimates, especially when motor torque is known.
8. Should I trust calculated torque alone?
No. Use it as an engineering estimate. Confirm the result with test data, supplier ratings, and traction limits before final design decisions.