ModelCalcs.uk
Scale Speed Calculator — Realistic Model Speed
Calculate how fast your model should move to match a real-world speed at scale. Essential for model railways and RC models.
How We Calculate This
Speed scales linearly — divide the real speed by the scale factor.
Formula
Scale speed = Real speed ÷ Scale factor
Example: A real train at 100 km/h on an OO gauge (1:76) layout:
100 ÷ 76 = 1.316 km/h = 365.5 mm/s on the model.
The result in mm/s is most practical for model railways, as it gives you the actual distance the model should travel per second on the layout.
Frequently Asked Questions
A real express train at 125 mph (201 km/h) at OO gauge (1:76) should travel at about 2.64 km/h or 734 mm/s on the layout. That is roughly 73cm per second — surprisingly fast for a model. Most modellers run their trains somewhat slower than true scale speed for visual appeal.
Yes, though RC cars are typically designed for exciting performance rather than scale realism. A 1:10 RC car doing 50 km/h is equivalent to 500 km/h at full size, which is beyond any real road car. Scale speed calculations help you set realistic speed limits for scale events.
Speed is distance per unit time. Since distance scales linearly with the scale factor (1:72 means 1/72nd the distance), and time is not scaled, speed also scales linearly. Weight scales cubically because it depends on volume (three dimensions), but speed is only one-dimensional.
Related Calculators
Scale Calculator
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Real to Scale Converter
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Scale to Real Converter
Convert a model measurement back up to find the real-world equivalent.
Scale Ratio Calculator
Find the scale ratio from a real measurement and its model equivalent.
Mixed Scale Calculator
Convert a measurement from one model scale to another without going back to real size.
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Last updated: February 2026
All calculations are estimates. Always verify quantities before purchasing materials.