What is the 30% rule for remodeling?

The “30% rule” is an informal remodeling guideline, not a universal building code or financial law. In some contexts, it means homeowners should avoid spending more than about 30% of a property’s value on a single renovation, especially when resale value is important. For example, a homeowner with a $400,000 property might use $120,000 as a rough upper reference point, though the appropriate amount depends on the neighborhood and project.

People also use “30% rule” to describe budgeting practices, such as reserving approximately 30% for unexpected costs. Neither interpretation should replace a project-specific budget, appraisal, contractor estimates, financing review, or local market analysis.