Guide
How to Calculate Gross Living Area (GLA)
Gross living area is finished, above-grade area measured from the exterior. Step-by-step calculation with what's included, what's excluded and an example.
Updated · FloorFigures
Short answer
Gross living area is the finished, above-grade area of a house, measured to the outside face of the exterior walls. Measure each level that is entirely above grade, add the levels, subtract openings to the floor below, leave out the garage, porches and any basement, and round to the whole square foot. A two-story house with 1,346.1 sq ft on the first floor and 1,105.8 sq ft upstairs has a GLA of 2,452 sq ft.
GLA is the single most important size figure in a US home appraisal, and it follows fixed rules: ANSI Z765-2021, which Fannie Mae and Freddie Mac require. Here is the method step by step, then a full worked example with a basement, a garage and a two-story foyer.
What counts as gross living area?
| In GLA | Not in GLA |
|---|---|
| Finished rooms on levels entirely above grade | Basements and walkout levels (reported as below-grade area) |
| Halls, closets, stairs and wall thickness | Garages, even finished or heated ones |
| Enclosed, year-round rooms finished like the house | Porches, decks, patios and balconies |
| Sloped rooms that are at least half 7 ft or higher (not the parts under 5 ft) | Openings to the floor below |
| Finished rooms connected by finished halls or stairs | Finished rooms reached only through unfinished space |
| Area under stairs on the lower level | Space with ceilings under 7 ft (6 ft 4 in under beams and ducts) |
The full rule set is in ANSI Z765 explained.
How to calculate GLA, step by step
- 1
Sort the levels
A level that is entirely above grade goes into GLA. A level that is even partly below grade, including a walkout basement, is below grade. See does a basement count. - 2
Measure the outside of each above-grade level
Measure at floor level to the exterior finished surface of the outside walls, to the nearest inch or tenth of a foot. Where the house meets the garage, measure to the drywall on the garage side, so the shared wall counts as living area. - 3
Work out each level's area
Split the outline into rectangles that only touch (no overlaps), multiply length × width for each and add them. Keep the decimals until the end. - 4
Subtract what isn't living area
Subtract openings to the floor below (see open to below). Leave out the garage, porches, decks and unfinished rooms. - 5
Check ceilings and connections
Finished area needs a 7 ft ceiling (6 ft 4 in under beams and ducts). In sloped rooms at least half must be 7 ft or higher, and nothing under 5 ft counts. A finished room you can only reach through the garage or an unfinished attic doesn't count. See ceiling height rules. - 6
Add the levels and round
Add the above-grade levels and round the total to the nearest whole square foot. Report below-grade finished area as its own figure.
Worked example: a two-story house with a basement
A two-story house. The main block is 40.5 ft × 30.2 ft on both floors, with a one-story family room bump-out of 12.3 ft × 10.0 ft on the first floor. The entry is a two-story foyer, 11.5 ft × 10.2 ft, open to the second floor. There is a basement under the main block, partly finished, and an attached two-car garage. Dimensions are to the exterior finished surface, in tenths of a foot.
| Area | Arithmetic | Sq ft | Where it goes |
|---|---|---|---|
| First floor, main block | 40.5 × 30.2 | 1,223.1 | GLA |
| First floor, family room | 12.3 × 10.0 | 123.0 | GLA |
| Second floor, main block | 40.5 × 30.2 | 1,223.1 | GLA |
| Second floor, foyer open to below | −(11.5 × 10.2) | −117.3 | Not counted upstairs |
| Gross living area | 1,223.1 + 123.0 + 1,223.1 − 117.3 | 2,451.9 → 2,452 | Above-grade finished |
| Basement, finished part | 24.0 × 30.2 | 724.8 → 725 | Below-grade finished |
| Basement, unfinished part | 16.5 × 30.2 | 498.3 → 498 | Below-grade unfinished |
| Attached garage | 22.0 × 22.5 | 495.0 → 495 | Not living area |
A few things to notice:
- The foyer counts once. Its floor is inside the first floor's 1,223.1 sq ft. Upstairs there is no floor, so its 117.3 sq ft comes off the second floor, which is 1,105.8 sq ft.
- The stairs aren't subtracted. The staircase between the floors counts on the second floor (the floor it descends from), and the space under it counts on the first. Measuring around the outside handles both.
- The basement stays out of GLA, finished or not. It is reported as 725 sq ft below-grade finished area and 498 sq ft below-grade unfinished.
- The garage is never living area. The wall it shares with the house is, because you measure the house to the drywall on the garage side.
- Round once, at the end. 2,451.9 becomes 2,452 sq ft.
Reported under ANSI Z765, that is: above-grade finished area 2,452 sq ft; below-grade finished area 725 sq ft. Never as one 3,177 sq ft figure.
What changes with UAD 3.6?
The term "GLA" is on its way out of the paperwork, though not the method. Fannie Mae's June 2025 Selling Guide update replaced "gross living area" and "basement" with above-grade and below-grade terms. The redesigned appraisal report (UAD 3.6), mandatory for new reports first submitted to UCDP on or after November 2, 2026, replaces the single GLA figure with six area fields:
| UAD 3.6 field | In the example |
|---|---|
| Finished Above Grade (what GLA was) | 2,452 sq ft |
| Finished Above Grade (Nonstandard) | 0 |
| Unfinished Above Grade | 0 |
| Finished Below Grade | 725 sq ft |
| Finished Below Grade (Nonstandard) | 0 |
| Unfinished Below Grade | 498 sq ft |
The garage isn't one of the six. "Nonstandard" is finished area that fails the ceiling-height rules or is reached through unfinished space. It stays out of Finished Above Grade but now has its own field. More in UAD 3.6 and square footage.
Calculating GLA from a floor plan
If you have the plan, FloorFigures does the arithmetic above for free in your browser. On a PDF it reads the printed dimensions to set the scale; press Shift+A to trace the building outline (it leaves out the garage and porch) or A to find every room. Put each floor on its own level, mark below-grade levels, cut out the foyer opening, and it reports above-grade and below-grade finished area separately, rounded to the whole square foot, with a statement to copy. Without a plan, type the dimensions into the GLA calculator.
Common GLA mistakes
| Mistake | Effect | Fix |
|---|---|---|
| Adding up room sizes from the plan | GLA comes out 10–20% low | Measure to the outside of the exterior walls |
| Counting a walkout basement as above grade | GLA too high | Any part below grade makes the level below grade |
| Counting a two-story foyer on both floors | GLA too high | Subtract the opening on the upper floor |
| Subtracting the stairwell upstairs | GLA too low | Stairs count on the floor they descend from |
| Counting a bonus room reached through the garage | GLA too high | Report it separately as nonstandard |
| Rounding each room before adding | Off by a few sq ft | Round the total once |
Questions
- What is gross living area (GLA)?
- Gross living area is the finished, above-grade area of a house, measured to the exterior finished surface of the outside walls. It includes every finished level that is entirely above grade and leaves out basements and other below-grade levels, garages, porches, decks, unfinished space and openings to the floor below. Fannie Mae now calls it above-grade finished area, and the UAD 3.6 appraisal report labels it Finished Above Grade.
- Does a finished basement count toward GLA?
- No. Under ANSI Z765-2021, a level that is wholly or partly below grade is a below-grade level, so a finished basement, walkout included, is reported as below-grade finished area on its own line. It is still finished space, and appraisers value it, but it is never added into gross living area.
- Is GLA measured from the inside or outside walls?
- From the outside. GLA is measured at floor level to the exterior finished surface of the outside walls, so it includes the thickness of the walls, halls, closets and stairs. That's why a house's GLA is larger than the sum of the room sizes printed on its floor plan.
- How is a two-story foyer counted in GLA?
- Once. The foyer's floor area counts on the first floor. On the second floor, the opening to the floor below is subtracted, because there is no floor there. An 11.5 ft by 10.2 ft foyer that is open to the second floor removes 117.3 sq ft from the second floor's area.
- Is GLA the same as total square footage?
- No. GLA is only the finished area on levels entirely above grade. Total finished square footage, as many listings show it, may add a finished basement. An appraisal under ANSI Z765 always reports above-grade and below-grade finished area separately, which is a common reason an appraisal's figure is lower than the listing's.
- Do stairs count in GLA?
- Yes. Under ANSI Z765, stair treads and landings count on the floor from which they descend, up to the area of the floor opening, and the area beneath the stairs counts on the level below. In practice you don't subtract the stairwell opening on the upper floor when you measure around the outside.