Why these tools exist
On most expensive decisions, everyone you would naturally ask has a stake in your answer. Your insurer pays less when you do not file. Your agent earns on the policy staying in force. A contractor earns on the repair being big. None of them are villains, but none of them are neutral either, and the arithmetic that would settle the question is rarely put in front of you.
So the rule here is simple. The aim is to make every number a tool produces reproducible by hand, the working is shown, and the assumptions link out to the regulator or agency they came from — state insurance departments, the CFPB, the Insurance Information Institute. Where a figure comes from an industry estimate rather than a regulator, the page says so plainly and lets you override it. Where a question genuinely cannot be answered by a calculator, the page says that too.