Develop a Web Based Calculator

We are looking to have a web-based calculator developed. The calculator will be similar to several carbon footprint calculators available online. This calculator will allow companies to calculate their Renewable Purchase Obligations (RPO). We will provide guidance, data (approximately 25 states each of which have a different %) and excel worksheets which show the calculation steps. The calculator should be able from our website, after a brief sign-on process. It should also collect the data entered by the user and make it available to us.