I needed a scale MPH calculator today. I know someone did one before and there was one or two floating around on the internet but I couldn't find them so I made my own in Microsoft Excel. It includes a scale MPH calculator for HO gauge, N gauge, and also "custom gauges" where you fill in your gauge denominator and it does the rest. It also includes a printable speed chart you can hang around your layout for quick reference. Feel free to use it as you see fit. Here's the link: http://www.boche.net/trains/Scale MPH calculator.xls I looked over the formulas and ran some numbers and they all look accurate. If anyone can see any mathematical errors, please let me know and I'll fix. Email: jason@boche.net Jas