Vehicle Engineering

Acceleration Calculator

Compute wheel force and acceleration in each gear from engine torque, gear ratios, differential ratio, tire size, and vehicle weight.

Inputs

Engine

RPM at which HP is measured (also used for speed)

Drivetrain

Typically 80–90% for manual, 75–85% for auto

Gear ratios

Vehicle

Same unit as curb weight

Tire

Results by gear

Gear Ratio Final
ratio		 Wheel torque
ft·lb		 Wheel force
lbs		 Speed @ RPM
mph		 Accel
g

Drivetrain Acceleration

Wheel torque = Engine torque × gear ratio × diff ratio × η Wheel force (lbs) = Wheel torque (ft·lb) / tire radius (ft) Acceleration (m/s²) = Wheel force (N) / total mass (kg) g = acceleration / 9.81 Tire radius (in) = rim_dia/2 + tire_width(mm) × aspect/100 / 25.4 HP ↔ Torque: T (ft·lb) = HP × 5252 / RPM
η = drivetrain efficiency Diff ratio = axle / differential gear ratio Final ratio = gear ratio × diff ratio 1 ft·lb = 1.35582 N·m 1 lbf = 4.44822 N