Convert Measurements

Many of my components (and some decals) are specified in terms of prototype dimensions. This page is to help you convert measurements between model size specified in mm, and prototype size specified in feet and inches. Conversions in a variety of scales are supported. If you set the scale to 1:1 then you can also convert between model mm and model inches, or between full-size mm and full-size inches. For quick reference a conversion table is provided below, or you can use the following calculator to convert individual measurements.

Conversion Calculator

Enter a model dimension value here to convert it to prototype size in inches, otherwise leave blank or set to zero.

Note: This value determines the direction of conversion: if a value other than zero is specified here, the feet/inches/fraction inputs are ignored.

Enter a prototype dimension value in one or more of these boxes to convert it to model size in mm. If you use the fraction box, be sure to select the appropriate fraction size too. Leave any unused boxes (including the Input mm one) blank or set to zero. The values for feet, inches and fraction will be converted to decimal inches and added together to produce the value to be converted.

Set the scale for the conversion here. The scales in mm are mm per foot. Use the 1:1 scale to simply convert between mm and inches.

Click here to calculate the result, once you have set the input boxes as required.

Conversion Table

The following table is to help convert scale inches into model dimensions (mm). To convert larger dimensions, multiply the scale (mm per ft.) by the number of whole feet, then add the remaining converted inches. The smallest dimensions have been rounded up where the accurate conversion would cause problems with the printing process and/or strength of the resulting component. In these cases the accurate conversion is given in parentheses – use the accurate version when converting dimensions greater than 1ft.

For those used to using metric units for full size measurments, 1 inch = 25.4 mm.

Scale in.Scale (mm : ft or ratio)
2 mm3 mm3.5 mm4 mm7 mm1:3210 mm1:22.516 mm
10.3 (0.17)0.3 (0.25)0.30.4 (0.33)0.60.80.91.11.3
20.4 (0.33)0.50.60.71.21.61.72.32.7
30.50.80.91.01.82.42.53.44.0
40.71.01.21.32.33.23.34.55.3
50.81.31.51.72.94.04.25.66.7
61.01.51.82.03.54.85.06.88.0
71.21.82.02.34.15.65.87.99.3
81.32.02.32.74.76.46.79.010.7
91.52.32.63.05.37.17.510.212.0
101.72.52.93.35.87.98.311.313.3
111.82.83.23.76.48.79.212.414.7
122.03.03.54.07.09.510.013.516.0

All model dimensions in mm.