Scale Conversion Calculator

Use this free scale calculator and scale converter to convert a measurement from one model scale to another. Enter the original length, its scale and the target scale to calculate the new model size. For ratios calculated from model and real measurements, use the Scale Factor Calculator; for map distances, use the Map Scale Calculator.

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Scale Calculator

Scale conversion tool

Convert

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Quick Model-to-Real Scale Ratio

Length on model :

Length in real life :

Model scale:

1 :

Need to calculate any missing value or learn the formulas? Open the full Scale Factor Calculator.

How to Use the Scale Converter

This scale conversion calculator changes a length from one model or drawing scale to another. It is useful when plans, model parts, miniatures or dimensions are supplied at a different scale from the one required for your project.

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Enter the measurement you want to convert.
Select its unit and enter the original scale denominator. For 1:24, enter 24.
Select the output unit and enter the target scale denominator.
Press Calculate to get the converted model or drawing length.

The converter accepts millimetres, centimetres, metres, kilometres, inches, feet, miles and nautical miles. Input and output units can be different.

Scale calculator converting model size to real size

Scale Conversion Formula

The calculator first restores the real-world equivalent of the input measurement and then divides it by the target scale:

target length = input length × input scale ÷ target scale

When the input and output use different units, the length is converted to a common base unit before this formula is applied.

Scale Converter Examples

Conversion	Calculation	Result
12 cm from 1:24 to 1:48	12 × 24 ÷ 48	6 cm
80 mm from 1:72 to 1:48	80 × 72 ÷ 48	120 mm
5 in from 1:50 to 1:100	5 × 50 ÷ 100	2.5 in
250 mm from 1:35 to 1:72	250 × 35 ÷ 72	121.53 mm

A conversion to a scale with a larger denominator makes the model smaller: converting 1:24 to 1:48 halves every linear dimension. Converting in the opposite direction doubles each length.

Where Scale Calculations Are Used

Model kits: convert aircraft, vehicle, ship and figure parts between modelling scales.
Model railways: compare HO, N, O and other railway dimensions.
Architecture: adapt dimensions between floor plans, elevations and presentation models.
Miniatures: resize furniture, scenery and printable templates.
Technical drawings: enlarge or reduce measured details while preserving proportion.

Tips for Accurate Scale Conversion

Enter only the denominator: use 72 for a scale written as 1:72.
Choose the unit that matches the measurement instead of converting it manually.
Measure the same feature at both scales, such as overall length or wingspan.
Keep extra decimal places for small parts and round only the final cutting dimension.
Remember that this tool converts linear dimensions; area and volume change by squared and cubed ratios.

Scale Calculator Questions

How do I convert from 1:24 scale to 1:48 scale?

Multiply the original model length by 24 and divide by 48. The result is half the original length because a 1:48 model is half as large linearly as the same object at 1:24.

Can the scale converter use different units?

Yes. You can enter a value in inches and receive the result in millimetres, for example. Select the correct input and output units before calculating.

What is the difference between this scale calculator and the scale factor calculator?

This page converts a known measurement from one scale to another. The dedicated scale factor tool finds the scale, model size or real size when any two of those values are known.

Need to Find an Unknown Scale?

For model, drawing and real-size calculations, use the dedicated Scale Factor Calculator. It calculates the missing value from any two measurements and includes formulas, worked examples and common modelling scales.