How does a General Contractor Estimate a job?

So how does a contractor estimate a job? We’re here in gilbert today at a home that was affected by water damage. We are working with the homeowners and insurance to get this repaired. There was some water damage that happened in this kitchen which required some flooring, drywall and cabinets and baseboards to be removed because of damage underneath this kitchen sink. It is our job to come in here and get an estimate over to the homeowner or insurance carrier so that they can understand what its going to cost to restore this home back to the original condition. First thing I do is sketch up the room with the square footage, linear footage and the cabinet area. Then I will go back to the office and write it up in the program we have. The system we use helps calculate all of the little things such as the filler pieces for the cabinet. Then we can get an estimate sent off to the homeowner and their insurance to get that approved.