Calculate wheel torque from engine torque, gear ratio, final drive and drivetrain efficiency, or work back from wheel torque to engine (crank) torque.
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- Wheel Over Point Calculator
Wheel Torque Formula
The calculator estimates total driven-wheel torque from engine torque, the transmission and final drive ratios, and an overall efficiency assumption:
- Where WT is the wheel torque
- ET is the engine torque (or motor torque for EVs)
- G is the transmission gear ratio, A is the final drive ratio, and η is the overall efficiency fraction from 0 to 1.
The full engineering formula accounts for gear ratios and transmission efficiency:
- ET = engine output torque (N·m)
- G = transmission gear ratio for the selected gear
- A = final drive (differential) ratio
- η = overall drivetrain efficiency assumption; use measured or specified data for the operating point
For example, 300 N·m of engine torque with a 3.5:1 gear ratio, 3.9:1 final drive and 0.94 efficiency gives 3,849.3 N·m of total driven-wheel torque. With a 0.78:1 gear ratio and the same other inputs, the total is 857.844 N·m. Neither value is the torque at each wheel; that requires the differential or motor torque split.
What is Wheel Torque?
Wheel drive torque is the turning moment delivered through a modeled drivetrain to its driven wheels. Gear ratios and losses can make it larger or smaller than engine torque. Tire radius, mass, grip, road resistance and rotational inertia also affect acceleration, so wheel torque alone does not determine performance.
The distinction matters because engine torque alone does not specify wheel torque. For two 400 lb-ft engines with the same transmission ratio and efficiency, a 4.10 final drive multiplies torque more than a 3.07 final drive. Comparisons between actual vehicles require all of those inputs.
Drivetrain Efficiency by Transmission Type
Losses depend on design, load, speed and temperature. The table below retains illustrative efficiency assumptions for comparing scenarios. These ranges are not universal specifications or a way to identify the efficiency of a particular transmission.
| Transmission Type | Illustrative Efficiency Range | Primary Loss Source |
|---|---|---|
| Manual (MT) | 94% to 97% | Gear mesh friction, bearing drag, synchronizer losses |
| Dual-Clutch (DCT) | 91% to 95% | Wet clutch pack drag (if wet type), hydraulic pump parasitic load |
| Traditional Automatic (AT) | 85% to 92% | Torque converter slip at partial lock-up, hydraulic pump, planetary gear friction |
| Continuously Variable (CVT) | 85% to 90% | Belt or chain slip on pulleys, clamping force hydraulic losses |
The illustrative values in the table refer to a transmission-only scenario. To combine separate component efficiencies, multiply them. For example, use η_total = η_transmission × η_final_drive when both are known. Do not apply a final-drive loss a second time if the entered overall efficiency already includes it.
Torque Multiplication Through Gears
Gears serve as torque multipliers. When a small gear drives a larger gear, rotational speed decreases while torque increases proportionally. In a vehicle, this multiplication happens twice: once in the transmission and again in the final drive (differential). The combined effect is called the overall drive ratio.
Consider a common six-speed manual with the following ratios paired with a 3.73:1 final drive and an engine producing 350 Nm:
| Gear | Gear Ratio | Overall Ratio (Gear x Final) | Wheel Torque at 350 Nm Engine Output (Nm, before losses) |
|---|---|---|---|
| 1st | 4.17:1 | 15.55:1 | 5,444 |
| 2nd | 2.34:1 | 8.73:1 | 3,055 |
| 3rd | 1.52:1 | 5.67:1 | 1,984 |
| 4th | 1.14:1 | 4.25:1 | 1,488 |
| 5th | 0.87:1 | 3.25:1 | 1,136 |
| 6th | 0.69:1 | 2.57:1 | 901 |
In first gear, the drivetrain multiplies engine torque by over 15 times. By sixth gear, that multiplier drops to about 2.5 times. This is the mechanical reason low gears produce strong acceleration while top gears are tuned for fuel-efficient cruising at highway speeds.
Wheel Torque in Electric Vehicles
Electric motors can produce substantial torque near zero speed, subject to current, inverter, thermal and control limits. Torque response and peak torque are vehicle-specific. The same gear-ratio and efficiency model applies to one motor drive path, but it does not describe transient control behavior.
As a hypothetical single-motor example, a 9:1 reduction and 375 N·m motor torque give 3,375 N·m before losses, or 3,037.5 N·m with an assumed 90% efficiency. This is an illustrative calculation, not a specification for a particular vehicle. Multiple motors or different drive paths must be modeled separately before combining their outputs.
A single fixed ratio sets one trade-off between wheel torque and motor speed. A transmission with multiple ratios can change that trade-off. This calculator uses the ratio entered for the operating point; it does not predict a vehicle’s motor torque curve or maximum speed.
From Wheel Torque to Traction Force and Acceleration
Wheel torque alone does not determine how fast a vehicle accelerates. The tire radius converts torque into a linear force at the road surface using the relationship:
Here F is the torque-limited force in newtons and r is the effective loaded tire radius in meters. A total torque of 3,000 N·m with a common 0.33 m radius corresponds to about 9,091 N. Actual acceleration depends on net force after road resistance, available grip, vehicle mass and rotational inertia.
For the same total wheel torque, a larger effective tire radius gives less torque-limited force at the road. A smaller radius gives more. This geometric relationship does not determine available tire grip or whether another tire size fits the vehicle.
Drivetrain Loss by Layout
Driveline layout changes the components in the torque path, but layout alone does not determine a loss percentage. The following retained ranges are illustrative modeling assumptions, not vehicle-specific measurements.
| Drivetrain Layout | Illustrative Total Loss | Key Components in Torque Path |
|---|---|---|
| Front-Wheel Drive (FWD) | 8% to 12% | Transaxle (combined gearbox and differential), half-shafts, CV joints |
| Rear-Wheel Drive (RWD) | 12% to 18% | Transmission, driveshaft, U-joints, rear differential, half-shafts |
| All-Wheel Drive (AWD) | 17% to 25% | Transmission, transfer case or center differential, front and rear driveshafts, two differentials, four half-shafts |
| Part-Time 4WD | 15% to 22% | Similar to AWD when engaged, but the transfer case typically uses a rigid coupling rather than a center differential |
Packaging affects the torque path: a transaxle can combine a gearbox and differential, while other layouts use separate shafts, differentials or couplings. Component count alone is insufficient to rank efficiency. Use data for the actual design and operating point rather than assigning losses solely from FWD, RWD or AWD labels.
Wheel Torque vs. Lug Nut Torque
The term wheel torque can also mean lug-nut tightening torque. That is a different use: drive torque turns the wheel, while tightening torque is applied to a fastener to create clamping preload. Torque and clamping force are different physical quantities.
For wheel-fastener tightening, follow the exact vehicle and wheel manufacturer’s torque, sequence and recheck instructions. This drive-torque calculator does not calculate lug-nut tightening specifications.
FAQ
Is this torque for each wheel? No. It is total output for the modeled drive path before allocation between wheels. Per-wheel values require the actual differential or motor torque split.
Are the default ratios and efficiency my vehicle’s values? No. The defaults are explicit modeling assumptions: 1.00 transmission ratio, 3.73 final drive and 85% efficiency. Use the actual ratios and operating-point data. Force mode additionally assumes one common effective loaded tire radius.
