SB4 Density Bonus Calculator
Estimate how many additional affordable housing units a faith-owned California property can develop under Senate Bill 4. This is a rough planning figure — actual entitlement requires site review.
SB4 DENSITY ESTIMATOR
ESTIMATED TOTAL UNITS
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BASE UNITS (BY RIGHT)
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SB4 BONUS UNITS
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EST. DUPLEXES (2-UNIT BLDGS)
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ROUGH CONSTRUCTION COST
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Estimates only — not a legal entitlement. Actual density depends on local general plan, fire access, parking requirements, and environmental review. Source: CA SB4 analysis framework.
Worked example
A 2.5-acre faith property zoned R-2 (8 units/acre) with 70% buildable area and 100% affordable housing commitment:
- Base units by right
- 14 units
- SB4 bonus units
- 14 additional units
- Total potential units
- 28 units
- Estimated construction cost
- $9.8M (at $350k/unit)
Sensitivity: Units by zoning and affordable %
| Zoning / Affordable | 50% | 75% | 100% |
|---|---|---|---|
| R-1 (4/acre) | 7 | 7 | 14 |
| R-2 (8/acre) | 14 | 14 | 28 |
| R-3 (15/acre) | 26 | 26 | 53 |
| R-4 (25/acre) | 44 | 44 | 88 |
Assumes 70% buildable area, 2.5-acre parcel. SB4 bonus only applies when 100% of units are affordable.
How it works
SB4 allows faith-owned land to bypass local zoning density limits when 100% of the housing is affordable. This calculator estimates the gap between what local zoning allows "by right" and what SB4 could permit.
Base Units = Acres × Zoning Density × Buildable %
SB4 Bonus = Base Units (when affordable % = 100%)
Total Units = Base + Bonus