How to Calculate FAR in NYC: AStraightforward Guide for Brownstone &Multifamily Owners

If you own or plan to buy property in New York City, Floor Area Ratio (FAR) determines nearly everything about your building’s development potential. From expanding a brownstone to adding additional units, FAR is the single most important zoning metric most owners don’t know how to evaluate.

At Raffi Group PLLC, we help property owners, buyers, and developers assess FAR every day. Below is a clean, accurate, attorney-approved breakdown anyone can use.

What Is FAR? (Explained Simply)

FAR — Floor Area Ratio — is the formula NYC uses to control building size and density.

Formula:

FAR × Lot Area = Maximum Allowable Floor Area

If your lot is 2,000 sq ft and the FAR is 2.0, you can legally build 4,000 sq ft total.

Step 1: Find Your Property’s Zoning District

Use the NYC Zoning & Land Use Map (ZOLA):

https://zola.planning.nyc.gov/

Search your address and note the zoning district (e.g., R6B, R7-2, R8B)

ZOLA shows your zoning district and FAR at a glance.

Step 2: Identify the FAR for Your District

On ZOLA, click “Zoning Documentation” to see:

● Residential FAR

● Commercial FAR

● Community facility FAR

For brownstones and small multifamily homes, residential FAR is typically the one that matters

ZOLA FAR table

Step 3: Multiply FAR × Lot Size

Example:

Lot size: 2,000 sq ft

Zoning FAR: 1.35

Max allowed: 2,700 sq ft

zoning map

Step 4: Subtract Existing Floor Area

Check:

● DOB BIS (Existing Floor Area)

● ACRIS documents

● Architectural plans

Remaining FAR = how much you can expand.

Common Issues Owners Miss (Legal Considerations You Should Know)

Even if zoning allows more square footage, additional rules may restrict your plans:

✔ Landmark or Historic District restrictions

✔ Height limits

✔ Rear yard requirements

✔ Sky exposure plane

✔ Structural capacity of brownstone foundations

✔ DOB discretionary approvals

This is where legal and architectural review becomes essential.

Why FAR Matters in 2025 and Beyond

NYC is entering a pro-housing era with major rezonings on the horizon. FAR now affects:

● Property valuations

● Air rights transfers

● Development feasibility

● Tenant buyout strategy

● Refinancing and long-term planning

A single FAR miscalculation can cost owners tens—even hundreds—of thousands of dollars.

Need a Professional FAR Analysis?

Our team regularly performs zoning and FAR evaluations for homeowners, investors, and developers