Model scale converter

The most common scales

Model railways: H0 = 1:87 (the most widespread), N = 1:160, Z = 1:220, TT = 1:120. Collector cars: 1:18, 1:24, 1:43. Aircraft: 1:48, 1:72, 1:144. Military and figures: 1:35 and 1:32.

How the ratio works

At 1:87 every real measurement is divided by 87: a 15-meter wagon becomes 17.2 cm. It works both ways: 1 cm on the layout equals 87 real cm, handy for designing believable buildings and dioramas.

Scale and gauge are not the same thing

This is the confusion that gets the wrong model bought in railway modelling. The scale is the reduction ratio (1:87); the gauge is the distance between the rails, measured in millimetres. The labels seen in shops, H0 and N, indicate both things at once: H0 is 1:87 on 16.5 mm track, N is 1:160 on 9 mm track.

From this comes the case that catches people out: there are H0 scale models that run on narrower track (H0m, H0e) because they reproduce real narrow-gauge railways. They're in the same scale, but they don't run on the same track. When buying, the number to check is the gauge, not just the label.

What precision makes sense

At 1:87 a millimetre of model is worth 8.7 centimetres in reality: roughly the thickness of a wall, and below that measure no printer and no mould can go. At 1:160 a millimetre is worth 16 centimetres, so details necessarily get simplified. Knowing what a millimetre is worth in your own scale is the quickest way to decide what to model and what to leave out.

The same rule works backwards, and it's the one you need when building: 1 cm on the layout is 87 real cm, so a two-metre door is 23 mm tall and a man of 1.75 is 20 mm. If the people on a layout look wrong, it's nearly always because that number wasn't checked.

The scales you meet, and why they're those

They aren't random numbers: they come from convenient measures in the systems where they were invented. 1:24 and 1:48 are half an inch and a quarter inch to the foot, which is why American modelling uses them everywhere; 1:72 is an inch to six feet; 1:43 comes from the fact that a toy car of that size ran on 0 gauge model railway track. The 1:35 of military vehicles and the 1:18 of collectors' cars are instead commercial conventions that caught on and stayed.

Nearby tools

To convert millimetres, centimetres and inches there is Length converter, and for areas Area converter. If you print the model in three dimensions, the cost is worked out by 3D printing cost; for the paper sizes to print the plans on Paper sizes.