Industry rule of thumb: estimates that exceed actual cost by more than ~10-20% require re-discussing scope

Claim: A widely cited working norm: standard estimates can run 10-20% over without re-negotiation; exceeding ~20% conventionally requires re-discussing scope with the customer.

Source: FreshBooks https://www.freshbooks.com/hub/estimates/are-estimates-binding

Confidence: Industry-consensus (working norm, not codified law).

Why this matters for Candid: Useful sanity check on how much the on-site calculator can be off before the gap becomes a customer-relationship problem in addition to a legal one.