House Square Footage Calculator
How many square feet is your house? Add every room below and we'll give you the whole-home total — using the same ANSI Z765 standard that US appraisers follow.
Last updated:Tip: If you only have the diameter, divide by 2 to get the radius.
L-shape = two rectangles sharing a corner.
Add one row per rectangle and we'll sum them.
What Counts Toward House Square Footage?
The widely accepted standard in the United States is ANSI Z765-2021. Here's the short version:
- Include all finished, heated, and permanently enclosed living areas — measured to the outside face of exterior walls.
- Exclude garages, unfinished basements, screened porches, open decks, and open stairwells (count the floor opening once).
- Low-ceiling areas (less than 5 ft tall) do not count; areas between 5 ft and 7 ft count only if at least half the floor has 7+ ft clearance.
- Finished basements are listed as "below-grade" square footage separately from above-grade living area.
How to Measure Your House
- Sketch each floor. Draw a simple floor plan for each level.
- Measure each room — length × width in feet.
- Don't forget hallways and closets; they count.
- Enter each room above. The calculator sums everything.
- Compare to any official records (your deed, MLS listing, tax assessor).
If your house has a complex footprint, use the L-Shape or Irregular tabs for each floor.
Typical Sizes of US Homes
| Home Type | Typical Sq Ft |
|---|---|
| Studio apartment | 400–600 sq ft |
| 1-bedroom condo | 600–900 sq ft |
| 2-bedroom starter home | 900–1,400 sq ft |
| 3-bedroom family home | 1,500–2,200 sq ft |
| 4-bedroom suburban | 2,200–3,200 sq ft |
| 5+ bedroom / luxury | 3,500–8,000+ sq ft |
The median new single-family home in the US is about 2,300 sq ft, per US Census Bureau construction data.
House Sq Ft vs. Listed Sq Ft
Real estate listings sometimes disagree with your measured total. The most common reasons:
- The previous owner included the garage or unfinished basement (incorrectly) in the listed size.
- The tax assessor used exterior measurements while you measured the interior.
- A finished basement was added later but never reflected in the official record.
If you disagree with a listing, measure using this tool and ask for a new appraisal based on ANSI Z765.
Why House Square Footage Matters
- Real estate pricing: comps are listed as $/sq ft.
- Insurance: rebuild cost estimates use sq ft × local construction cost.
- Tax: many municipalities assess property tax based partly on finished area.
- HVAC sizing: one ton of A/C serves roughly 500–600 sq ft.
- Renovation: every contractor bid uses sq ft as the baseline.
Step-by-Step: Measuring a Two-Story Home
- Sketch the first-floor footprint. Measure each exterior wall and label lengths in feet.
- Break the shape into rectangles. An L-shaped home is two rectangles; a complex plan may need five or six.
- Enter each rectangle in the irregular calculator above. The total is the first-floor area.
- Repeat for the second floor. If the footprints differ, measure each level separately.
- Subtract open two-story spaces once — a 10 × 10 atrium counts on one floor, not both.
- Add above-grade totals together. Keep basement square footage as a separate number.
What ANSI Z765 Actually Says (Plain English)
- Measure to the outside face of exterior finished walls.
- Include finished stair openings on the floor they depart from, not both.
- Include fully enclosed and heated spaces only.
- Attic/bonus: count areas with ≥ 7 ft ceiling plus areas at 5–7 ft if 50% of the floor has ≥ 7 ft clearance.
- Report above-grade and below-grade square footage separately.
- Open decks, garages, and screened porches are excluded.
Frequently Asked Questions
How is sqft calculated for a house?
Measure every finished, heated room and add the areas. Exclude garages and unfinished basements. Follow ANSI Z765 for US real estate listings.
How to calculate sqft of a house from the outside?
Measure each exterior wall to the outside face, multiply length × depth of each rectangular section, and sum all sections. This matches what an appraiser does.
Does the garage count toward the square footage of a house?
No — garages are listed separately. A converted garage that is heated, finished, and permanently enclosed does count.
What about my basement?
Only if it's finished and heated. Listings separate "above-grade" from "below-grade" sq ft so buyers can compare apples to apples.
How do I measure sqft of a two-story house?
Measure the first-floor footprint, then the second-floor footprint, and add them. Subtract any open two-story atrium so you do not double-count the floor opening.
Does a finished attic count?
Under ANSI Z765, areas with ceilings below 5 ft do not count. Portions with 5–7 ft count only if at least half the floor has at least 7 ft of clearance.
Why does my listed sqft differ from what I measured?
Common reasons: the previous owner included the garage or unfinished basement, the tax assessor used exterior vs. interior measurement, or a finished basement was added but never recorded.
How is sqft used in real estate pricing?
Comparable sales are normalized as dollars per square foot. A much higher $/sq ft usually means upgraded finishes or a better location. Use our cost per sq ft calculator to compare listings.