Handy Gadgets

Grade Calculator

Convert rise/run into grade, or convert grade plus rise into run or grade plus run into rise.


  • Rise and run can be any units, as long as they are both the same.
  • Enter values in any two fields, then click outside the form; the missing value will be calculated.
  • To clear the fields and reset the calculator, click in any field.





Scale Dimension Calculator/Converter

Convert real dimensions to model dimensions and vice-versa, plus convert English to Metric and vice-versa, all at the same time. Dimensions are calculated and converted depending on which value is entered first.

Example 1: To determine what a 40-foot boxcar would actually measure in N scale, select the scale, enter "40" in the Real feet field, then click Calculate.

Example 2: To determine what a 6-inch-long Z scale model structure scales up to in actual feet and inches, select Z scale, enter "6" in the Model inches field, then click Calculate.


  • The field containing the starting value will be highlighted.
  • You can change the modeling scale after performing a calculation, and it will immediately recalculate starting with the original value entered.
  • Real feet and inches can be entered at once, but only real meters or millimeters can be entered.
  • To clear calculated values and reset the calculator, click in any field.

Modeling scale:

Real feet:

Real meters:

Real inches:

Real mm:

Model inches:

Model mm:

Scale Drawing Converter

Do you have a drawing in one scale and wish to convert it to another? Use this converter to obtain the percentage required to enlarge/reduce it. Percentage is calculated as the scale selections are made.

Drawing scale:

Modeling scale:


Resistor Decoder

Use this color-based decoder to determine the values of typical resistors. Value is calculated as the color selections are made.

First band:

Second band:

Third band:

Fourth band:


Copyright 2006-2018 by David K. Smith. All rights reserved.