Does this calculator tell me if I comply with my local zoning?

No. This calculator provides an informational estimate based only on the areas you enter. It does not look up or verify actual zoning codes, and it cannot determine official compliance. Zoning definitions of 'coverage' vary between jurisdictions. Always check your local zoning ordinance and consult with planning officials or professionals for compliance determinations.

What counts as building coverage in real zoning rules?

It depends on your jurisdiction. Most codes count the footprint of all buildings, including the main house, garages, and accessory structures. Some also include covered porches, carports, and roof overhangs beyond a certain depth. Others may have separate limits for 'building coverage' and 'impervious coverage' (which includes driveways and patios). Always check your specific local code.

Is building coverage ratio the same as floor area ratio (FAR)?

No. Building Coverage Ratio (BCR) measures only the ground-floor footprint area as a percentage of lot area. Floor Area Ratio (FAR) measures the total floor area of all stories combined relative to the lot area. A 2-story building with a 1,000 sq ft footprint has a BCR based on 1,000 sq ft, but a FAR based on 2,000 sq ft total floor area.

Can I use this calculator instead of professional advice?

This calculator is for informational planning purposes only. It cannot replace professional advice from licensed architects, surveyors, planners, or local zoning officials. For permit applications, design decisions, or compliance questions, always consult qualified professionals who understand your local regulations.

Why do cities limit building coverage?

Coverage limits serve several purposes: managing stormwater runoff (less impervious surface means more rainwater can soak into the ground), preserving green space and trees, maintaining neighborhood character and openness, ensuring adequate light and air reach adjacent properties, and providing visual separation between buildings.

What if I exceed my coverage limit?

If your planned design exceeds the coverage limit, you may need to reduce building footprints, remove certain structures, or apply for a variance. Variances require demonstrating hardship and going through a public hearing process. Consult with your local planning department or a land use attorney to understand your options.

Should I include my pool in the coverage calculation?

It depends on your local code. Some jurisdictions count pools as impervious coverage (separate from building coverage), while others may not count them at all. Pool houses or cabanas typically count as building coverage. Check your zoning ordinance or ask your local planning department for guidance.

How do I find my lot area?

Your lot area should be listed on your property survey, deed, or plat map. You can also check your property tax records or county assessor's website. For irregular lots, a professional survey may be needed to determine the exact area. Do not rely on estimates from online mapping tools for permit applications.

Can I run different scenarios with this calculator?

Yes! You can add or remove buildings, adjust footprint sizes, and change the coverage limit to compare different design options. Use the scenario label field to name each calculation for easy reference. This helps you explore 'what if' questions before consulting with design professionals.

Building Coverage Ratio Calculator

Q: What is building coverage ratio?

Building coverage ratio (BCR), also called lot coverage, is the percentage of a lot that is covered by buildings. It is calculated by dividing the total building footprint area by the lot area. For example, a 2,000 sq ft building footprint on a 10,000 sq ft lot has a 20% coverage ratio.

Calculate the percentage of your lot covered by buildings and other covered structures. Compare against zoning coverage limits to understand your site's development potential.

Lot Information

Lot Area (sq ft) *

Enter lot dimensions (optional, for reference)

Building Footprints

Main Building

Label (optional)

Footprint Area (sq ft) *

Include in coverage

Other Covered Areas

Include other covered areas (patios, carports, etc.)

Some jurisdictions count covered patios, carports, and overhangs

Coverage Limit (Optional)

Coverage Limit to Compare Against (%)

Enter a coverage limit (like 35%) to compare your design against. This is for reference only and is not looked up from zoning codes.

Scenario Label (Optional)

Calculate Building Coverage

Enter your lot area and building footprints to see how much of your lot is covered by buildings. Optionally compare against a coverage limit.

Lot Area

Enter sq ft

Building Footprints

Add buildings

Fill in the form and click "Calculate Coverage" to see results

Understanding Building Coverage Ratio

What Is Building Coverage Ratio?

Building Coverage Ratio (BCR), also known as lot coverage or building coverage, is a measure of how much of a lot is covered by buildings and sometimes other covered structures. It is expressed as a percentage of the total lot area.

Formula: Building Coverage Ratio = (Total Building Footprint Area / Lot Area) x 100%
Example: A 2,000 sq ft building footprint on a 10,000 sq ft lot = 20% coverage
Purpose: Zoning codes use coverage limits to control density, ensure green space, manage stormwater runoff, and maintain neighborhood character

How Building Coverage Differs from FAR (Floor Area Ratio)

Building Coverage Ratio and Floor Area Ratio (FAR) are related but distinct concepts:

Building Coverage Ratio (BCR)

Measures footprint area (ground floor only)
Considers horizontal extent of buildings
Controls lot "openness" and green space
A 2-story and 10-story building with same footprint have same BCR

Floor Area Ratio (FAR)

Measures total floor area across all stories
Considers vertical extent (building height/stories)
Controls overall density and bulk
A 10-story building has much higher FAR than a 2-story with same footprint

Together, BCR and FAR shape how buildings can be designed. A low BCR with high FAR encourages taller, slimmer buildings with more open space. A high BCR with low FAR results in sprawling, low-rise development.

Why Cities Use Coverage Limits

Municipalities establish building coverage limits for several important reasons:

Stormwater Management: Impervious surfaces (buildings, pavement) prevent rainwater from absorbing into the ground, increasing runoff and flooding risk
Green Space Preservation: Coverage limits ensure some portion of each lot remains open for landscaping, trees, and natural areas
Neighborhood Character: Prevents lots from being completely filled with structures, maintaining visual openness and setbacks
Light and Air: Ensures adequate sunlight and ventilation reach neighboring properties
Privacy: Creates separation between buildings on adjacent lots

Typical Items That May Count Toward Coverage

Different jurisdictions have varying definitions of what counts as "covered area." Common items that may be included:

Often Included

Main house footprint
Attached garages
Detached garages and accessory buildings
Covered porches and carports
Attached decks with roofs
Pool houses and cabanas

Sometimes Included (Varies)

Roof overhangs beyond a certain depth
Pergolas and arbors
Open decks without roofs
Swimming pools
Driveways and patios (sometimes separate impervious limit)
Underground structures

Important: Always check your local zoning code for the specific definition applicable to your property. This calculator lets you include or exclude items based on your local rules.

Typical Coverage Limits by Zone Type

Coverage limits vary significantly based on zoning district and location. Here are some general ranges (always verify with local codes):

Zone Type	Typical BCR Range	Notes
Rural/Agricultural	5-15%	Large lots, minimal coverage
Single-Family Suburban	25-40%	Most common residential zones
Single-Family Urban	35-50%	Smaller lots, higher density
Multi-Family Residential	40-60%	Apartments, condos
Commercial	50-80%	Retail, office buildings
Downtown/Mixed-Use	70-100%	Urban cores may allow full coverage

Limitations of Simple Coverage Calculators

This Calculator is for Planning Only

It uses only the areas you enter and does not look up actual zoning rules
Local definitions of "coverage" vary and may include or exclude items differently
Some jurisdictions have separate limits for building coverage and total impervious coverage
The tool cannot verify measurements or account for irregular lot shapes
Variances, overlays, and special districts may modify base requirements
This is not a substitute for professional advice from architects, surveyors, or planners

Tips for Using This Tool

Know your lot area: Check your property survey or deed for accurate lot dimensions
Measure footprints carefully: Use building plans or measure the ground-floor outline of each structure
Check your local code: Find out what items count toward coverage in your jurisdiction
Run multiple scenarios: Try different layouts to see how adding or removing structures affects coverage
Consult professionals: For permit applications or design decisions, work with an architect or planner

Frequently Asked Questions

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