Nationwide ADU is a free, data-driven ADU feasibility calculator built to help homeowners across all 50 states understand what it actually costs to build an accessory dwelling unit on their property — before they spend money on architects, contractors, or permits.
Nationwide ADU is researched, written, and maintained by one person — not a content agency or an anonymous team. Every state page, cost figure, and guide on this site is built and kept current by hand, starting from the same questions a homeowner would ask a contractor directly.
Getting an accurate ADU cost estimate used to require calling multiple contractors, waiting weeks for bids, and navigating confusing permit fee schedules. Most online resources gave national averages that didn't reflect the real cost differences between California's high-cost coastal markets, Texas's mid-range metros, and the more affordable construction environments in the Midwest and Southeast.
We built Nationwide ADU to give homeowners a reliable starting point in under 60 seconds — using real regional cost data, not generic national estimates.
Cost estimates are based on regional construction cost benchmarks, permit fee data from municipal sources, and project type multipliers derived from contractor pricing patterns. All estimates carry a ±15% variance and are intended as planning tools, not contractor bids. We update our data regularly to reflect market changes.
Nationwide ADU connects homeowners who complete our calculator with licensed local ADU contractors. If you are a contractor interested in receiving pre-qualified leads, contact us at support@nationwideadu.com.
Questions, feedback, or partnership inquiries: support@nationwideadu.com