A bid is a formal, fixed-price offer to perform defined work — used in public construction procurement where multiple contractors compete on identical scope. A quote is an informal cost indication, often verbal — useful for ballpark assessment, not for financial planning. An estimate is a calculated cost projection based on a defined scope of work, quantity takeoffs, and current market pricing — the document that should form the basis of any construction contract. At RainFire Builders, we use the term estimate and apply the discipline of a formal estimate to every project: written scope, line-item costs, stated exclusions, and an explicit contingency. You should insist on this standard from any contractor you hire.