Model Train Scale Speed Calculator
Convert prototype locomotive speed to true model speed for HO, N, O, G, S, and Z scales.
Shows results in mph, inches per second, and cm per second.
A model train running at prototypical speed should cover scale distance in scale time. If a prototype locomotive runs at 60 mph and your layout is HO scale (1:87), the model should travel at 60/87 = 0.69 mph on the track.
Model speed (mph) = prototype speed (mph) / scale ratio Model speed (in/s) = model_mph × 5280 × 12 / 3600
That works out to roughly 12.2 inches per second for a 60 mph prototype in HO — which looks surprisingly fast on a typical basement layout. Most operators run 20–30 mph scale equivalent for a more visually natural pace.
Common scale ratios: Z (1:220) — smallest commercial scale N (1:160) — space-efficient, popular for large layouts in small rooms HO (1:87) — most popular scale worldwide OO (1:76) — British standard, very close to HO S (1:64) — American Flyer standard O (1:48) — Lionel and other traditional manufacturers G (1:22.5) — large scale, often used outdoors
Whether to run prototypically is a real debate in the hobby. On a 4×8 layout, a 60 mph freight train crosses from one end to the other in roughly 4 seconds. Most modelers find 25–35 mph scale equivalent looks more convincing at typical viewing distances.
DCC decoders with programmable speed tables let you calibrate the motor to hit specific scale speeds at specific throttle positions. This calculator tells you your target in/s; the decoder gives you the control to match it.