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:
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 — 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.