This is the link to several calculator tools http://www.modelbuildings.org/free-calculator-tools.html

Track Grade Calculator

One of the biggest mistakes when planning a model railroad is to misjudge the required gradients (grades) for the layout. Even though the track plans might look good sketched on paper, the big question is; how practical will they be when converted from paper to track, wood, and foam on a model railroad?

The track may need to be longer than on the sketched plan if the locomotive is to pull several cars up and down an incline without mishap, or the wheels spinning through lack of traction. Having a locomotive cough, splutter, and eventually stall on a grade can be very disheartening, especially if it results in a derailment or burnt out motor.

Helix Design Calculator

This page includes a lot of helpful information and sketches to assist you with planning construction of a helix for your model railroad layout.

Firstly, here is a tool to help you with important measurements including the track radius and required headroom. This helix calculator will do most of the mentally difficult calculations for you with a simple click of your mouse.

Enter the details and it will calculate measurements for percent grade, ring diameter, number of rings needed, along with the quantity of material needed. Simply enter the numbers you want and adjust them until you obtain results that will be suitable for what you want to construct.

Scale Conversion Calculator

With this calculator you can convert real (prototype) size to scale size, or convert scale size to real size.

Scale to Scale Converter

Convert inches to metrics, and convert the size of model railroad scales to other scale sizes (e.g. convert HO scale to OO gauge, or N scale).

Scale Speed Calculator

Measure scale speeds for trains to cover the distance from point A to point B.