Calculate the house exterior area, building footprint exterior, or exterior wall area using the tabs below.

Exterior Square Footage Calculator

Calculate house square footage from exterior dimensions, quick building footprint area, or exterior wall square footage.
Measure each rectangular section from the outside of the building. Add more sections for L-shaped or irregular layouts. Stories let you estimate total square footage from one exterior footprint.
Exterior-Measured Sections
Add Section
Length (ft)
Width (ft)
Stories
Example: a 24 by 24 exterior footprint with 2 stories gives 1,152 sq ft.
Use this quick mode when you only need building footprint area from the outside dimensions of one repeating structure.
Estimate gross and net exterior wall area for siding, cladding, or paint. Net wall area subtracts windows, doors, and other openings.

Results

Related Calculators

Exterior Square Footage Formula

The following formula is used to calculate the exterior square footage of a property lot (the land area not covered by building footprints).

ESF = TLA - BA

Variables:

  • ESF is the exterior square footage (e.g., sq ft)
  • TLA is the total land area of the lot (same area units as ESF)
  • BA is the total building footprint area (sum of building footprints on the lot, in the same area units as ESF)

To calculate the exterior square footage, subtract the building footprint area from the total land area. (If you need the footprint area of a rectangular building, you can compute it as BA = L × W.)

What is Exterior Square Footage?

Exterior square footage refers to the portion of a property’s lot that is outside of (and not covered by) building footprints. This can include elements such as the yard, driveway, patio, deck, porch, pool, and other outdoor features. It is often used in real estate and site planning because the amount of usable outdoor space can contribute to how a property is valued and used.

How to Calculate Exterior Square Footage?

The following steps outline how to calculate the Exterior Square Footage (ESF).

  1. First, determine the total land area of the lot (TLA).
  2. Next, determine the total building footprint area (BA). (If a building is rectangular, its footprint area can be calculated as L × W.)
  3. Next, gather the formula from above: ESF = TLA − BA.
  4. Finally, calculate the Exterior Square Footage (ESF).
  5. After inserting the values for TLA and BA into the formula and calculating the result, check your answer with the calculator above.

Example Problem:

Use the following variables as an example problem to test your knowledge.

Total land area (TLA) = 200 sq ft

Rectangular building footprint: L = 10 ft and W = 8 ft, so BA = 10 × 8 = 80 sq ft. Therefore, ESF = 200 − 80 = 120 sq ft.