Vehicle Speed Calculator
SI
Imp
Imperial
Inputs
View results
Engine speed
(n_e)
Crankshaft speed.
rpm
Tire diameter
(D)
Rolling tire diameter. Use measured rolling diameter for precision.
in
Transmission ratio
(G)
Selected gear ratio. Overdrive gears are less than 1.0.
Final drive ratio
(F)
Axle or differential ratio.
Transfer ratio
(T)
Transfer-case or auxiliary ratio. Use 1.0 if none.
Results
Default result
Edit inputs
Vehicle speed
(v)
69.12
mph
Pass
Also computed
Wheel speed
(n_w)
893.7
rpm
Overall ratio
2.797
Tire circumference
81.68
in
Method notes
2 notes
Assumes no clutch slip, torque-converter slip, tire growth or rolling-radius change under load.
Use manufacturer revs-per-mile data when speedometer calibration matters.
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