Model Scale Calculator

Work out model scale instantly with clear inputs, formula shown and shareable results.

About Model Scale Calculator

A scale of 1 : n means every model measurement is n times smaller than reality, so model = real / n and real = model × n. The same units must be used on both sides.

Formula

Scale conversion

model = real / n, real = model × n

Worked example

With the default values below, Model Scale Calculator returns Model length of 137.931034. Change any input above and every figure here is recalculated in your browser.

Inputs used

Real-world lengthminimum 0: 12,000
Scale 1 : nminimum 1: 87
Model length to convert backminimum 0: 100

Results

Model length: 137.931034
Real length for the given model length: 8,700.000000
Scale: 1 : 87
Model size as a percentage of real: 1.149425 %

Step by step

1Values used
2Scale conversion
3Model length= 137.931034
4Real length for the given model length= 8,700.000000
5Scale= 1 : 87
6Model size as a percentage of real= 1.149425 %

Assumptions and limits

The result is derived only from the 3 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
Figures are rounded for display to 6 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

12000 mm at HO scale 1 : 87?

12000 / 87 ≈ 137.93 mm on the model.

Common model railway scales?

OO is 1:76.2, HO is 1:87, N is 1:148 to 1:160 and O is 1:43.5 to 1:48 depending on the region.