Convert Excel App to PHP/AJAX

I have a fairly complex application written in Microsoft Excel which has a lot of different formulas, and drop-down menus within a form. Users can change drop-down menu values and these change the output that appears on a graph which draws values from inbuilt formulas. I need this converted to an online app. I will need it to be done in PHP but the graph can be done in (I am guessing) ajax, but maybe coders will have a better suggestion. This will eventually be integrated into a website which already runs off a mysql database, however this application may or may not need to be database driven. I will need to find out what is best. I am not at liberty to post the Excel file publicly, but for anyone interested in this project, I can send it privately if you place your estimated bid. I am happy for bids to be adjusted accordingly after you have viewed the file and assessed scope of work properly. I am also unsure as to time it will take, so willing to consider all reasonable time estimates also.