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Lot Coverage Calculator

Calculate existing and proposed building coverage percentages, test a new addition, and compare your totals with the maximum coverage allowed by your local zoning rules.

Instant resultsNo sign-upSquare feet or square meters
Step 1: enter your measurements

Calculate Your Lot Coverage Percentage

Use verified parcel and building measurements. Leave the maximum percentage blank if you only need to calculate coverage, or enter your local limit to check how much capacity remains.

Property and project details

Your inputs are calculated in your browser and are not submitted to us.

Building footprints only.

Calculation only. A zoning-compliant footprint may still be restricted by setbacks, easements, height, open space and drainage rules.

Your lot coverage results

Enter your lot size and project footprints, then select Calculate coverage. Try Load example to see a complete sample.

Method and worked examples

How to Calculate Lot Coverage

Lot coverage percentage = counted covered area ÷ applicable lot area × 100. The numerator depends on your city's zoning definition. Building footprint coverage is often different from impervious coverage, which may include driveways, patios and parking.

  1. Confirm the survey or zoning lot area used by the local code.
  2. Add all existing footprints the ordinance counts, measuring the plan-view area.
  3. Subtract any counted structures or surfaces that will be removed.
  4. Add the new proposed counted area, without double counting overlap.
  5. Divide existing and proposed totals by lot area and multiply by 100.
  6. If you know the permitted maximum, compare your proposed total with that limit.

Also review our detailed lot coverage calculation guide for more zoning examples, limits and exceptions.

What counts toward lot coverage?

Use the local ordinance's definition rather than assuming the same rules apply nationwide. Some jurisdictions limit building footprints while others include specific hardscape areas.

Site featureWhat to check before counting it
House, garage or shedWhether the entire exterior footprint and projections are counted.
Covered porch or carportWhether coverage extends to roof edges, posts, or enclosing walls.
Driveway or parking padWhether the code includes hardscape in lot coverage or only in a separate impervious-area calculation.
Uncovered patio, deck or pergolaLocal exclusions based on roof cover, surface, height or permeability.
Swimming pool and pool deckWhether the water surface and surrounding pavement are treated separately.

Maximum lot coverage versus building coverage and impervious area

Building coverage usually addresses horizontal building footprints. Impervious surface coverage addresses locally defined runoff-producing surfaces. Floor area ratio (FAR) divides regulated floor area across levels by lot area. These calculations are not interchangeable.

For one concrete zoning example, New York City's maximum lot coverage table distinguishes some residential zoning districts and lot types. Those rules are not national defaults. Check the current zoning requirements for your own city or county.

How to find the maximum lot coverage for your property

Search the official zoning map for the property's district, then check the applicable development standards and definitions. The lot type, permitted use, easements, setbacks, open-space requirements and existing nonconforming conditions can affect what is actually possible. If the local maximum is unknown, you can still use this tool to calculate a percentage without showing an approval status.

More planning help
Lot Coverage Calculation Guide →Formula, zoning definitions, examples and permit issues. Impervious Surface Calculator →Review roofs, driveways, walkways, paving and open space. Floor Area Ratio Calculator →Compare regulated building floor area with lot area. Setback Requirements Guide →Understand setbacks alongside maximum coverage. ADU Site Plan Services →Plan accessory dwelling placement and footprint. Residential Site Plan Services →Scaled permit plans with existing and proposed conditions.
Answers before you apply

Lot Coverage Calculator FAQs

What is the formula for lot coverage percentage?

Divide the area counted as covered under the applicable zoning definition by the relevant lot area, then multiply by 100. For example, 1,800 ÷ 6,000 × 100 = 30% coverage.

Can I calculate coverage without knowing the zoning maximum?

Yes. Leave the maximum limit field blank. The tool will show the existing and proposed percentages without claiming that either figure is permitted.

Does a driveway count toward lot coverage?

It depends on how your city defines lot coverage. A driveway may be outside a building coverage calculation but included in a broader lot coverage or impervious-surface calculation.

How do I calculate maximum building coverage?

Multiply the applicable lot area by the allowed percentage expressed as a decimal. For example, an 8,000 sq ft lot with a hypothetical 35% limit permits 2,800 sq ft of counted area before other restrictions.

Do I count a two-story home's area twice?

Generally not when the rule is based on ground-level footprint. Floor area ratio can count areas on multiple floors. Follow the exact definitions in the applicable ordinance.

Does a covered patio, pergola or pool count?

Codes differ on roofed porches, open pergolas, pool water surfaces and decks. Ask the local zoning office or review its definitions to determine which components to include.

Is this calculator the same as an impervious coverage calculator?

No. Impervious coverage may include roofs, concrete, asphalt and other surfaces that restrict water infiltration. For a separately regulated impervious limit, use our dedicated impervious-surface calculator.

Can I use these results for a building permit?

The results are estimates based on measurements you enter, not a zoning determination or approved drawing. A permit application may require a scaled site plan with a coverage schedule, documented source areas, and additional local information.

Need a Permit-Ready Site Plan?

We can prepare a scaled plan showing existing and proposed structures, lot boundaries, setbacks and a coverage table where the jurisdiction requires it. Send your survey and permit checklist for a project-specific scope review.

Get a Free Scope Review →
This calculator is for preliminary planning only. Calculations remain in your browser. It does not verify your zoning district, survey, local coverage exclusions or permit eligibility. Actual requirements are determined by the reviewing authority.