How do you calculate price per square foot?

Price per square foot equals the sale price divided by the above-grade gross living area (GLA). Appraisers use GLA. Not total finished area, not lot size. Because it is the most consistent and comparable measure across properties. Finished basement square footage is typically valued separately at a lower rate.

FAQ / How to calculate price per square foot

Valuation · 5 min read

How to Calculate Price Per Square Foot

Q: What is the formula?

Price per square foot = Sale price ÷ Above-grade GLA.

Q: Why appraisers use above-grade GLA. Not total finished area?

Appraisers compare properties using above-grade gross living area (GLA) because it is the most consistent measure across different property types. Below-grade space. Including finished basements. Is valued separately and at a lower rate per square foot.

Price per square foot is one of the most commonly cited real estate metrics, and one of the most commonly misunderstood. The formula is simple, but what you put in the denominator changes everything.

The formula

Price per square foot = Sale price ÷ Above-grade GLA

Example: A home sells for $420,000 with 1,800 square feet of above-grade GLA. Price per square foot = $420,000 ÷ 1,800 = $233/sq ft. (The U.S. median home is about 2,299 sq ft: see average square footage of a house for data by state and home type.)

That is it. The complexity is in knowing which square footage to use.

Why appraisers use above-grade GLA: not total finished area

Appraisers compare properties using above-grade gross living area (GLA) because it is the most consistent measure across different property types. Below-grade space: including finished basements. Is valued separately and at a lower rate per square foot.

Mixing above-grade and below-grade square footage into a single price-per-square-foot calculation makes comparisons misleading. A 2,000 sq ft home with 800 sq ft of finished basement is not equivalent to a 2,000 sq ft all-above-grade home, but they look identical if you only look at total finished area.

For a meaningful comparison, use GLA in the denominator and adjust separately for finished basement square footage.

What to include in GLA

Include: All finished, heated above-grade living space: main level, upper floors, finished attic areas with adequate ceiling height
Exclude: Garages, unfinished attic, basement (finished or not), covered porches, decks
Measured from: Exterior wall dimensions (ANSI Z765), not interior

See: What counts as GLA? for a full breakdown.

How to handle finished basements in the calculation

Finished basement square footage is real value: it just sells at a discount relative to above-grade space. Appraisers handle it by:

Calculating price per square foot using above-grade GLA only
Identifying the finished basement area as a separate line item
Applying a dollar-per-square-foot adjustment for the basement: typically 25 to 60 percent of the above-grade rate, depending on market

Example: If above-grade GLA commands $230/sq ft and the market shows finished basements trading at 40% of that, a 900 sq ft finished basement adds approximately $92/sq ft × 900 = $82,800 in contributory value.

Why Zillow and MLS price-per-square-foot numbers are often wrong

Zillow, Redfin, and most MLS systems calculate price per square foot using whatever square footage the listing agent entered: which may include basement area, may be from county records, or may simply be wrong. These numbers are not standardized.

When comparing homes for a purchase decision or an appraisal, always verify what square footage was used in the denominator. A $180/sq ft listing that includes 1,000 sq ft of finished basement is very different from a $180/sq ft listing that is all above-grade.

Getting an accurate square footage for the calculation

The price-per-square-foot metric is only as reliable as the GLA number you feed into it. For a property you are buying, selling, or appraising:

Do not rely on county assessor records: they are frequently outdated or use inconsistent methodology
Do not rely on MLS square footage: agents pull from various sources with no consistency requirement
Use a floor plan from a scan service (CubiCasa, iGUIDE, Matterport) or a licensed appraiser sketch, measured to ANSI Z765 standards

Get accurate GLA before you calculate

Upload a floor plan and get ANSI-compliant above-grade GLA and basement area separately, so your price-per-square-foot calculation uses the right number.

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