FAR Calculator: Calculate Floor Area Ratio Online

Calculate Floor Area Ratio (FAR) quickly and accurately to understand how much building floor space is allowed on a given plot of land.

The FAR Calculator helps you work out the relationship between a building’s total floor area and the size of the land it sits on. Floor Area Ratio, often called FAR or FSI (Floor Space Index) in some regions, is an important planning and development metric used in architecture, construction, and real estate.

It is commonly used to determine how much built-up area is permitted on a site under local zoning or planning rules. Whether you are evaluating a development opportunity, checking compliance, or planning a new project, this tool makes FAR calculations simple and instant.

What Is Floor Area Ratio (FAR)?

Floor Area Ratio is the ratio between the total gross floor area of a building and the total area of the plot or lot.

The formula is:

FAR = Total Floor Area ÷ Plot Area

For example, if a building has a total floor area of 10,000 sq ft and the plot area is 5,000 sq ft, the FAR is:

10,000 ÷ 5,000 = 2.0

A higher FAR generally means denser development, while a lower FAR means less built area relative to the size of the land.

How It Works

Enter the total floor area of the building and the plot area of the site. The calculator then divides the floor area by the plot size to produce the Floor Area Ratio instantly.

1. Enter the total floor area
2. Enter the total plot or lot area
3. Click calculate
4. View the resulting FAR value

This makes it easy to assess site density, compare development options, or check whether a design may fit local planning limits.

Key Features

• Instant FAR Calculation: Quickly calculate floor area ratio in seconds.
• Simple Formula-Based Tool: Uses the standard FAR formula used in planning and construction.
• Useful for Property Development: Helps assess building density and development potential.
• Helpful for Compliance Checks: Useful when reviewing planning regulations or zoning requirements.
• Fast, Browser-Based Tool: No installation or software required.

Common Uses of FAR

Floor Area Ratio is used in many property and construction-related scenarios, including:

• Estimating how much floor space can be built on a plot
• Checking zoning and planning compliance
• Comparing development opportunities across multiple sites
• Evaluating density for residential, commercial, or mixed-use projects
• Understanding land use restrictions before design or purchase decisions

Calculation Examples

Here are a few simple examples:

• Total Floor Area: 12,000 sq ft
• Plot Area: 6,000 sq ft
• FAR: 12,000 ÷ 6,000 = 2.0

• Total Floor Area: 8,000 sq m
• Plot Area: 4,000 sq m
• FAR: 8,000 ÷ 4,000 = 2.0

• Total Floor Area: 15,000 sq ft
• Plot Area: 10,000 sq ft
• FAR: 15,000 ÷ 10,000 = 1.5

These examples show how the ratio increases as more floor space is built relative to the size of the site.

Why FAR Matters

FAR is one of the key measurements used to control urban density and land use. Local authorities often set maximum FAR limits for different areas to regulate building scale, open space, traffic impact, and overall development intensity.

Understanding FAR can help architects, builders, developers, investors, and property buyers make better decisions about what can realistically be built on a site.

When to Use This Tool

• Planning a new building project
• Checking if a proposed design fits land-use rules
• Assessing development potential before buying land
• Reviewing building density for real estate analysis
• Working with planning, zoning, architecture, or construction data

Why Use This FAR Calculator

Manually calculating Floor Area Ratio is straightforward, but doing it repeatedly across multiple plots or design options can slow down planning work. This calculator provides a fast and accurate way to get the result instantly without errors.

It is especially useful for architects, planning consultants, developers, surveyors, students, and anyone involved in land use or building design.

Frequently Asked Questions

What does FAR mean?

FAR stands for Floor Area Ratio. It measures the relationship between a building’s total floor area and the size of the plot it occupies.

Is FAR the same as FSI?

In many places, yes. FAR and FSI (Floor Space Index) are often used interchangeably, although terminology may vary by country or local authority.

How do you calculate FAR?

Divide the total floor area of the building by the total plot area:

FAR = Total Floor Area ÷ Plot Area

What does a FAR of 2.0 mean?

A FAR of 2.0 means the total building floor area is twice the size of the plot area. For example, a 5,000 sq ft site could support 10,000 sq ft of total floor space, subject to local rules.

Does a higher FAR mean a taller building?

Not necessarily. A higher FAR allows more total floor area, but that could be spread across more floors, a larger footprint, or a combination of both, depending on planning rules and design constraints.

Why is FAR important in real estate and planning?

FAR helps determine development potential, site density, and compliance with local zoning regulations. It is a key factor in land valuation, design feasibility, and project planning.

Can I use this tool with square feet or square metres?

Yes. You can use any area unit as long as both the floor area and plot area use the same unit.