A scale calculator converts a measurement from one scale to another, for example from the size of a real object to the size of its model.
A faster way to convert scales
Whether you build model aircraft, paint miniatures, lay out a model railroad or draw architectural plans, this tool turns real-world measurements into scaled sizes (and back again) without any maths. Choose your scale from the preset list instead of memorising ratios, mix metric and imperial units, and read the result the moment you type.
How to convert a scale
- Enter your measurement. Type the real-world or model size and choose a unit: mm, cm, m, inch or feet.
- Pick the “From” scale. Use Real life (1:1) for a real object, or choose the model scale you are starting from.
- Pick the “To” scale. Select a preset such as 1:72, 1:35, HO or N, or type any custom ratio.
- Read the result. The converted size and scale factor update instantly, with no calculate button.
Common scales reference
How big a 10 m (1000 cm) real object becomes at popular scales:
| Scale | Common use | 10 m real → model |
|---|---|---|
| 1:18 | Diecast cars, large models | 55.6 cm |
| 1:35 | Military models, tanks | 28.6 cm |
| 1:48 (O) | Aircraft, O-scale trains | 20.8 cm |
| 1:72 | Aircraft, vehicles | 13.9 cm |
| 1:87 (HO) | Model railroad (HO) | 11.5 cm |
| 1:100 | Architecture | 10.0 cm |
| 1:160 (N) | Model railroad (N) | 6.3 cm |
| 1:220 (Z) | Model railroad (Z) | 4.5 cm |
Popular scale calculators
Jump straight to a ready-made calculator for your scale:
More scale tools
Frequently asked questions
How do I convert a real size to a model scale?
Set the “From” scale to Real life (1:1), enter the real-world measurement, then set the “To” scale to your model scale (for example 1:72). The model size appears instantly.
What is a scale factor?
A scale factor is the ratio between a model and the real object. At 1:48, the scale factor is 1/48: every part of the model is 48 times smaller than the real thing.
Can I convert between two different scales?
Yes. Set the “From” scale to the original scale and the “To” scale to the target scale (for example from 1:48 to 1:72), and the calculator keeps the real object the same size while resizing the model.
Which units are supported?
Millimeters, centimeters, meters, inches and feet. You can mix units freely: for example, enter meters and read the result in centimeters.
What is a scale calculator?
A scale calculator converts a measurement from one scale to another. Enter a real-world or model size, choose the scales, and it works out the matching size. It is useful for scale models, model railroads, architecture and maps.
How do I find the scale of a model?
Divide the real length by the model length. If a real car is 4.8 m and the model is 20 cm (0.2 m), the scale is 4.8 ÷ 0.2 = 24, so the model is 1:24.
Is 1:72 bigger or smaller than 1:48?
1:72 is smaller. The larger the second number, the smaller the model. A 1:48 model is 1.5 times larger than the same subject at 1:72 (72 ÷ 48 = 1.5).
How do I scale a drawing or model up?
To enlarge, set the “From” scale to your current scale and the “To” scale to a smaller ratio number. For example, going from 1:72 to 1:48 makes everything 1.5 times bigger.