I regret to inform you that it is unlikely you would be able to make a spreadsheet to calculate "reasonable atty's fees". You could make one for filing for reasonable atty's fees, but the reasonableness adds in the ambiguity.
When I clerked for a Fed. Judge, more or less I would skim through the time spent by the attorney(s) and the time spent by the paralegal(s).
Then when considering the case and its complexity (esp. after reviewing all the pleadings, etc.) and it didn't seem especially excessive, I would recommend accepting it.
If I thought it was excessive, like they were really milking their claim for atty's fees, I would review more thoroughly. In that case, I would suggest knocking down hours for certain times spent or changing certain activities from Atty to Para, such as "Atty: Check PACER/CMECF for case status - 0.5hr" I would knock down to 0.1 and change to the paralegal, Which could change that one entry from like $300 down to like $60. Do that four times and you get a grand. Same with large times spent "filing" documents, it doesn't take a long time to file documents as long as cmecf is up. I usually wouldn't consider adjusting "skilled" entries, like Analyzing, Drafting, Editing, Strategizing, etc., unless they seems especially egregious (considering case complexity).
Also, like commented above, when there are an excessive number of attorneys, the time may get knocked back as the number of hours spent on it may be considered unreasonable.
Then, after I went through everything, I would give my bench brief to the Judge, he would likely make changes to it and give it back. Then I would draft the Order, he would sign, and it would be entered.
