Scale Model Dimension Calculator
Convert a real-world measurement into its scale-model size (or back) for any modelling scale like 1:24, 1:87 or 1:144.
How it works
Model = real ÷ scale · Real = model × scale
A scale of 1:n means one unit on the model equals n units in reality, so you divide a real measurement by n to shrink it down and multiply a model measurement by n to size it up. The same factor applies to every linear dimension — length, width and height — which keeps the model in proportion. Areas shrink by n² and volumes by n³, so weight and material drop far faster than length.
Worked example
At 1:24 scale, a real car 180 inches long becomes 180 ÷ 24 = 7.5 inches on the model. Reversing it, a 7.5-inch model part represents 7.5 × 24 = 180 inches in the real world.
Sources: Scale (ratio) — Wikipedia
Frequently asked questions
What does a scale like 1:87 mean?
It means the model is 1/87th of the real object in every linear dimension. A 1:87 (HO scale) model of a 43.5-foot rail car would be 43.5 ÷ 87 = 0.5 feet, or 6 inches, long.
Does the scale change area and volume too?
Yes, but not linearly. Linear dimensions divide by n, areas divide by n², and volumes (and roughly weight) divide by n³. A 1:10 model has 1/100th the surface area and 1/1000th the volume.
Which units should I use?
Any, as long as both sides use the same unit — the ratio is unitless. Enter inches to get inches, or millimetres to get millimetres; just keep the real and model measurements in the same unit.
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This calculator is for educational purposes. Double-check important results before acting on them.