MITCalc is a professional, multilanguage-prepared package of mechanical calculations that includes solutions for gearing, belt and chain drives, springs, beams, shafts, bolt connections, shaft connections, and many other things. The calculations support both imperial and metric units and are processed according to ANSI, ISO, DIN, BS, CSN, and Japanese standards. The sophisticated interaction with many 2D (AutoCAD, AutoCAD LT, IntelliCAD, Ashlar Graphite, TurboCAD) and 3D (Autodesk Inventor, SolidWorks) CAD systems allows the relevant drawing to be developed or 3D models to be inserted in a few seconds. MITCalc is developed in Microsoft Excel. It allows not only easy user-defined modifications and expansions but also mutual interconnection of the calculations, which is unique in the development of tailor-made complex calculations.