Find Your Development Potential
Instant zoning analysis, state law pathways, and pro forma projections for any California parcel.
285,000+
Parcels loaded
36
Zoning districts analyzed
4
State law pathways evaluated
How It Works
Enter an Address
Type any Marin or Sonoma County street address or APN. Autocomplete finds the right parcel instantly.
Get Your Analysis
Zoning, state law eligibility, fees, and environmental data — pulled automatically.
Run the Numbers
Editable pro formas and sensitivity analysis for every development scenario.
Zoning Analysis
Know exactly what you can build. Zone standards, directional setbacks from PostGIS geometry, buildable footprint and max building square footage — with parcel map overlay.
- Height limits, FAR, lot coverage, and density standards
- Geometry-based directional setbacks (front, rear, sides)
- Buildable polygon overlay on interactive parcel map
State Law Pathways
Every development right, automatically checked. California's housing laws create opportunities beyond local zoning — we evaluate them all.
- SB 9 two-unit + lot split eligibility
- ADU/JADU by-right sizing and placement
- Density Bonus tiers and Builder's Remedy windows
Pro Forma Engine
From concept to numbers in minutes. Itemized fee breakdowns across agencies, location-tier cost adjustments, and side-by-side scenario comparison.
- Fee aggregation from schools, water, sewer, and permits
- Location-tier multipliers for Marin sub-markets
- Editable construction costs and revenue assumptions
Sensitivity Analysis
See where deals break — and where they work. Color-coded matrices showing how construction cost swings and cap rate shifts affect your return.
- Cost variance from -15% to +15% in 5% increments
- Cap rate sensitivity across market conditions
- 49-cell matrix with instant visual feasibility read
Every option, side by side
SB 9 duplex, lot split, ADU, JADU — each scenario shows units, fees, construction cost, projected revenue, and return on cost. Select any option to run a full pro forma.
Spot the winner instantly: a JADU conversion at 83.6% ROC vs. a ground-up duplex at -26.9%. The math matters more than the zoning code.
Geometry-based buildable area
Not just numbers from a table — BuildByRight calculates your actual buildable footprint from real parcel geometry, with directional setbacks computed from PostGIS.
Front, rear, and side setbacks are applied to the real parcel shape — not a rectangle approximation. The result: a precise buildable polygon with maximum square footage and the binding constraint identified.
See where deals break
The sensitivity matrix shows how construction cost and cap rate shifts affect your return. Green means go, red means the numbers don't work — across 28 scenarios at once.
A 15% swing in construction cost or 50 basis points in cap rate can flip feasibility. This is how you know before you commit.
California's Housing Laws Are Changing the Math
State preemption is creating development rights that go beyond what local zoning allows. If you're not checking state law pathways, you're leaving value on the table.
SB 9 (2022)
Two-unit + lot split by right on any single-family lot statewide.
AB 1893 (2025)
Builder's Remedy reform and clarification for non-compliant jurisdictions.
SB 543 (2026)
Expanded ADU by-right allowances for qualifying properties.
SB 35/423
Streamlined ministerial approval for qualifying projects through 2036.
Ready to analyze a parcel?
See a full analysis — zoning, state law pathways, pro forma, and sensitivity — on a real parcel.