House Square Footage Calculator
Estimate a home's finished square footage floor by floor, the way appraisers measure it.
ANSI Z765 rules
What counts in a home’s square footage
A home’s square footage usually means its finished, above-grade living area, measured along the outside walls.
Included in the total
- Finished rooms above ground, including hallways and closets
- Stairs, counted once, on the floor they lead down from
- Sloped rooms where at least half the floor has 7 ft of headroom and no part is under 5 ft
Left out or reported separately
- Finished basement, reported as separate below-grade area
- Rooms with ceilings under 7 ft
- Garage, unfinished attic or basement
- Open space above a two-story foyer
These rules come from the ANSI Z765 standard, which Fannie Mae requires appraisers to use. Read Fannie Mae’s summary.
Step by step
How to measure your home
Measure each level outside
Run the tape along the exterior walls, to the nearest inch.
Split odd shapes into rectangles
Enter each rectangle as its own area.
Set each area’s type
Living area, finished basement, unfinished or garage.
Flag low ceilings
Finished space under 7 ft doesn’t count as living area.
Read the total
Rounded to the nearest square foot, as appraisers report it.
Worked example
A two-story home with a basement and garage
- Main floor 40 × 30 ft
- 1,200 sq ft
- Upper floor 40 × 24 ft
- 960 sq ft
- Living area
- 2,160 sq ft
- Finished basement separate
- 1,200 sq ft
- Garage not counted
- 484 sq ft
Worked example
Example: a two-story home with a basement
Exterior measurements, rounded to the nearest inch, then added floor by floor.
| Area | Size | Square feet | Living area? |
|---|---|---|---|
| First floor | 40 × 30 ft | 1,200 | Yes, above grade |
| Second floor | 40 × 24 ft | 960 | Yes, above grade |
| Finished basement | 40 × 30 ft | 1,200 | Reported separately |
| Attached garage | 22 × 22 ft | 484 | No |
| Gross living area | 2,160 sq ft + 1,200 sq ft below grade | ||
At a $450,000 sale price this home is about $208 per square foot of living area. Dividing by all 3,360 finished sq ft instead would show $134, which is why listings and appraisals report basements apart. Try it in the price per square foot calculator.
Key terms
Gross living area, above grade and below grade
Gross living area (GLA)
Finished, heated, above-grade space measured on the exterior. It is the number appraisers use to compare homes.
Below-grade area
Any level partly below ground, even with windows or a walk-out door. It is listed on its own line, finished or not.
Gross building area
Used mostly for multi-family and commercial property. It includes all floors and is measured on the exterior walls.
FAQ
House square footage questions
This tool gives an estimate. For a sale, refinance or appraisal, have a licensed appraiser measure the home.
What is included in the square footage of a house?
The reported square footage is usually the finished, above-grade living area, measured along the outside walls. It includes finished rooms, hallways and stairs, but not garages, unfinished space or basements, which are reported separately.
Is a basement included in square footage?
Under the ANSI Z765 standard, a finished basement is reported separately as below-grade area and is not added to the above-grade living area. Listings sometimes show both, so check which figure you are comparing.
Is the garage included in square footage?
No. A garage is not finished living space, so it is not counted in the home's living area.
Do you measure square footage from inside or outside walls?
For a whole house, measure along the outside walls. Room sizes in listings are usually measured inside, so adding up room sizes gives a smaller number than the home's square footage.
Do stairs count in square footage?
Yes. Stairs are counted on the floor they lead down from, so they are included once, not on both levels.
Why is my home's square footage different from the listing?
Different methods give different answers. A listing may include a basement, measure inside the walls, or use old records. Measuring the outside walls level by level, as this calculator does, follows the appraisal standard.
Is an unfinished attic or bonus room counted?
Only finished space with heating and at least 7 ft of ceiling height over most of the floor counts. An unfinished attic is left out; a finished bonus room over the garage counts if it meets those rules.
Are sunrooms, porches and decks included?
Open porches and decks are not living area. A sunroom counts only if it is finished, heated and built like the rest of the house.
What is gross living area?
Gross living area (GLA) is the finished, above-grade square footage of a home, measured from the outside walls. Appraisers use it to compare homes.