Develop a Mac Application

Fedex shipping calculator for dimensional weight I need an application to take BULK (1000s of fields) product dimensions (weight; L x W x H) from an excel input file, calculate them into dimensional weight and then reference against Fedex ground and Fedex Smart Post tables using either an excel sheet calculation or an api application. There will be just one zone (from CA to NY) for simplicity and conservative shipping calculations. The calculations should occupy 3 output fields....one, fed ex ground, two, fedex smart post and the third field being the lowest of the two by which the margin calculation can be based on. The output of either an excel based calculator or an api application needs to be in an excel sheet format. The original excel input file that I have with the product dimension information along with many other columns of information needs to be transferred to the shipping calculation output excel sheet in such a manner to line up the columns to make an immediate margin calculation based of the shipping information. The purpose of this is to allow for final product margin calculations (with shipping being the last variable in the equation). This application needs to work on a Mac or it can be web-based.