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Affordable Housing Density Bonus Calculator

Including affordable housing unlocks density bonuses that can make projects pencil.

%
%
$
$

Project value lift

$4,750,000

Total units

125

Net project value

$42,750,000

How the math works

Total = base × (1 + bonus). Value = market × $market + affordable × $affordable.

100 × 1.25 = 125 total. 100 × $380k + 25 × $190k = $38M + $4.75M = $42.75M.

How to Use

  1. Enter base unit count.
  2. Enter affordable % set-aside.
  3. Enter density bonus %.
  4. Enter value per market rate unit.
  5. Enter value per affordable unit.
  6. Read net project value.

Frequently Asked Questions

Density bonus value?

California SB35: up to 35% density bonus for affordable housing set-aside. DC IZ: 20-35% bonus. SF: up to 50% bonus for specific site types. Denver: 15-25%. Key: density bonus ABOVE base entitlement. Land cost basis is fixed; additional units at same land price = high marginal yield.

Economics?

100-unit base × 20% affordable = 80 market + 20 affordable. Density bonus 25% = 125 total units: 100 market + 25 affordable. Additional 20 market-rate units on same land = huge marginal return. Affordable compensation: 60-80% AMI rent (vs 100% AMI for market). Reduction in gross revenue: 2-5% typical when well-structured with density bonus.

Eligibility?

Program criteria: multifamily 5+ units, specific zoning districts, near transit (TOD), or meeting specific affordability standards. Ground-up multifamily: eligible. Mixed-use: typically eligible. Single-family: usually not. Hotel: rarely. Affordable levels: 30%, 50%, 60%, 80% AMI typical thresholds. Income verification required for residents.

Compliance?

30-year affordability covenant typical. Deed-restricted. Monitoring: annual reporting to housing authority. Income verification for new tenants. Rent limits enforced. Resale: affordable units stay affordable (or sold back to authority). Non-compliance: city can sue, impose penalties, foreclose. Professional housing authority partnership recommended for management.

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