How the Rules Work

In Part One, we looked at why zoning exists and how it evolved. Now, we’ll look at how New York City’s zoning rules function in practice.

At first glance, zoning can look like a code language, with its letters and numbers such as R6A, C6-4 or M1-6. But once you understand what those codes mean, the system becomes much easier to interpret.

New York City’s Zoning Districts

New York City currently has 122 zoning districts, grouped into three main categories:

• Commercial (C)
• Residential (R)
• Manufacturing (M)

Each district specifies:

• What uses are permitted
• How large a building may be
• How tall it may rise
• How it must fit within its surroundings

Commercial Districts

There are currently 72 commercial zoning districts. A commercial district is typically written in a format such as C6-4 or C6-4A. Here’s what that means:

• C designates a commercial district.
• The first number generally relates to the type or scale of commercial activity.
• The second number corresponds to allowable density; higher numbers allow more floor area and typically less required parking.
• A letter suffix (such as A) indicates a contextual district designed to match surrounding building scale.

When residential use is permitted within a commercial zone, a residential equivalent applies to determine housing density.

Residential Districts

There are 38 residential zoning districts, written in formats such as R6 or R6A.

• R designates residential use.
• The number indicates density, with higher numbers permitting more floor area.
• A letter suffix (A, B, X) indicates contextual districts with specific height and bulk rules designed to align with neighborhood scale.

Manufacturing Districts

There are 12 manufacturing zoning districts, written in formats such as M1-6.

• M designates manufacturing use.
• The first number reflects the intensity of permitted industrial activity (M1 being the least disruptive, M3 the most).
• The second number corresponds to density.

Residential use is generally not permitted in manufacturing districts, though certain special districts, such as parts of SoHo and Long Island City, include hybrid designations that combine manufacturing and residential.

How Density Is Measured: Floor Area Ratio (FAR)

One of the most important concepts in zoning is Floor Area Ratio, commonly referred to as FAR. FAR determines how much total building area can be constructed on a site. The calculation is straightforward:

FAR × Lot Size = Maximum Buildable Floor Area

For example, if a site measures 100 feet by 100 feet, then it contains 10,000 square feet of land.

• FAR of 1.0 allows 10,000 square feet of building area.
• FAR of 2.0 allows 20,000 square feet.
• FAR of 10.0 allows 100,000 square feet.

That floor area can be distributed vertically or horizontally, depending on height limits and other zoning rules. FAR does not automatically determine height. A building’s height is influenced by additional factors such as setbacks, contextual zoning and sky exposure plane requirements.

Understanding FAR helps explain why two buildings on similarly sized lots may look dramatically different.

Why This Matters in Tribeca

Zoning codes are not abstract. The difference between contextual and non-contextual districts can significantly shape our neighborhood’s future form.

In Part Three, we’ll apply these concepts specifically to Tribeca and examine what the current zoning rules allow.