What most people know as an estimate, is often a ProfessionalGuesstimate made by a professional with what information and tools are available to that person.  This happens when it is not at all clear as to what the actual man-hours and material costs will be.  Often this is the only cost figure given, and often this is the number that results, in the end, as profit or loss for a transaction between individuals in this type of business agreement.

Reminder: Business is not for the faint of heart.

----
See Also: GiveMeEstimatesNow