Square Footage Calculator
Pick a shape, then enter feet and inches (leave inches at 0 if you measured in whole feet).
Conversions
Square Footage Calculator
Quick answer: square footage = length × width, with both in feet. Convert inches first by dividing by 12: a room 12 ft 6 in × 10 ft is 12.5 × 10 = 125 ft² (13.9 yd², 11.6 m²). Split L-shaped or irregular rooms into rectangles and add the areas.
Measure any floor in feet and inches — rectangles, L-shaped rooms, circles, triangles, and trapezoids — add up to five more rooms, and get the total in square feet, square yards, square meters, and acres, with an optional cost per square foot.
L-shaped room split into two rectangles
How to calculate square footage
Square footage is a floor area: how many 1 ft × 1 ft squares fit inside a space. For a rectangle you only need two measurements. Every other floor plan can be broken into rectangles, triangles, and circles, then added back together.
Length (ft) × Width (ft) = ft²
convert inches first: feet + inches ÷ 12
- Sketch the space and mark where it can be split into simple shapes.
- Measure each section wall to wall at floor level, to the nearest inch.
- Convert inches to decimal feet. 3 in = 0.25 ft, 6 in = 0.5 ft, 9 in = 0.75 ft. Ten feet six inches is 10.5 ft, not 10.6 ft.
- Multiply length × width for each rectangle (use the shape formulas below for others).
- Add the sections and subtract anything that will not be covered, such as a fixed kitchen island.
- Convert if needed: ÷ 9 for square yards, × 0.0929 for square meters, ÷ 43,560 for acres.
Worked example: an L-shaped living room
The main part of the room is 14 ft 6 in × 12 ft, with a 6 ft × 8 ft 3 in dining alcove off one end (see the diagram). Flooring is quoted at $5.25 per square foot installed.
- Section A: 14.5 × 12 = 174 ft²
- Section B: 6 × 8.25 = 49.5 ft²
- Total: 174 + 49.5 = 223.5 ft² = 24.83 yd² = 20.76 m²
- Cost: 223.5 × $5.25 = $1,173 before any waste allowance
Area formulas by shape
All dimensions in feet. Each example matches what the calculator returns for the same inputs.
| Shape | Formula | Example | Area |
|---|---|---|---|
| Rectangle / square | length × width | 12 × 10 | 120 ft² |
| L-shape | (A length × A width) + (B length × B width) | 14.5 × 12 + 6 × 8.25 | 223.5 ft² |
| Circle | π × diameter² ÷ 4 | 10 ft diameter | 78.54 ft² |
| Triangle | base × height ÷ 2 | 12 base, 8 high | 48 ft² |
| Trapezoid | (side 1 + side 2) ÷ 2 × height | (10 + 14) ÷ 2 × 8 | 96 ft² |
Square footage conversion table
| Square feet | Square yards | Square meters | Acres |
|---|---|---|---|
| 100 | 11.11 | 9.29 | 0.0023 |
| 144 (12 × 12) | 16.00 | 13.38 | 0.0033 |
| 500 | 55.56 | 46.45 | 0.0115 |
| 1,000 | 111.11 | 92.90 | 0.0230 |
| 1,500 | 166.67 | 139.35 | 0.0344 |
| 2,000 | 222.22 | 185.81 | 0.0459 |
| 2,500 | 277.78 | 232.26 | 0.0574 |
| 5,000 | 555.56 | 464.52 | 0.1148 |
| 10,000 | 1,111.11 | 929.03 | 0.2296 |
| 43,560 | 4,840.00 | 4,046.86 | 1.0000 |
How to measure a room
Measure at floor level, from the face of one wall to the face of the opposite wall, and run the tape past the baseboards rather than over them. Take each dimension in two places — near each end of the wall — because few rooms are perfectly square; use the larger number when you are buying material. A laser distance measurer makes one-person measuring easier and is accurate to within about 1/16 in over room-size distances.
Include closets and alcoves that will get the same flooring, and measure doorways to the center of the door where one floor type meets another. Write every measurement on your sketch as feet and inches so you can convert it once, at the end.
Irregular rooms
Split the plan into pieces the calculator handles. An angled bay wall is a rectangle plus two triangles; a curved bump-out is a rectangle plus half a circle (π × diameter² ÷ 8). Enter the main area with the shape selector, add the other pieces as extra rooms, and type any area that will not be covered — a fixed island, a fireplace hearth — in the subtract box. For flooring, add 5–10% for cuts on a straight layout and 10–15% for diagonal or herringbone patterns.
Square feet of a house: what counts
For a whole home, the number on a listing or appraisal is usually gross living area, which is measured differently from a single room. The ANSI Z765 standard, which many U.S. builders and appraisers follow, measures to the exterior finished surface of the outside walls and counts only finished, heated space. Below-grade levels are reported separately from above-grade area, and garages, unfinished basements, porches, and decks are excluded. Finished areas generally need a ceiling height of at least 7 ft; under a sloped ceiling, no part lower than 5 ft is counted. Open-to-below areas such as a two-story foyer count only on the floor below. County records, MLS rules, and lenders do not all use the same method, which is why two sources can report different square footage for the same house — treat this as general guidance and ask how a figure was measured.
Common square footage mistakes
- Treating inches as decimals. 10 ft 6 in is 10.5 ft. Entering 10.6 overstates a 10 ft 6 in × 12 ft room by 1.2 ft².
- Mixing up square and linear feet. A 10 ft × 10 ft room is 100 square feet, while its perimeter (for baseboard) is 40 linear feet.
- Forgetting closets and nooks. A 3 ft × 6 ft reach-in closet adds 18 ft² of flooring that is easy to miss.
- Ordering exactly the measured area. Flooring, tile, and sod all need an allowance for cuts and breakage — use the waste field.
- Comparing room totals to the listed house size. Room-by-room interior measurements always add up to less than exterior-wall gross living area because wall thickness is excluded.
- Using square feet where a supplier wants square yards. Carpet is often priced per square yard: divide square feet by 9.
Square footage FAQ
How do you calculate square footage?
Multiply the length by the width, both measured in feet. A room 12 ft 6 in long and 10 ft wide is 12.5 × 10 = 125 square feet. For L-shaped or irregular spaces, split the floor into rectangles, find each area, and add them together.
How do I calculate square feet with feet and inches?
Convert the inches to a decimal of a foot by dividing by 12, then multiply. 14 ft 6 in becomes 14.5 ft and 8 ft 3 in becomes 8.25 ft, so the area is 14.5 × 8.25 = 119.6 square feet. Do not write 14 ft 6 in as 14.6 ft.
How many square feet is a 12x12 room?
A 12 ft × 12 ft room is 144 square feet, which is exactly 16 square yards or about 13.4 square meters. If you are buying flooring, add 5 to 10 percent for cuts, so plan on roughly 151 to 159 square feet of material.
How do you find the square footage of an irregular room?
Break the floor into rectangles, triangles, and circles, calculate each piece with its own formula, and add them; subtract built-ins such as a kitchen island. For example, a 14.5 × 12 ft main area plus a 6 × 8.25 ft alcove is 174 + 49.5 = 223.5 square feet.
Is the garage included in the square footage of a house?
Usually not. Under the ANSI Z765 measuring standard used by many builders and appraisers, only finished, heated living space counts, measured to the outside of the exterior walls, while garages, unfinished basements, porches, and decks are reported separately. MLS and county assessor rules vary, so check how a listing was measured.
How many square feet are in an acre?
One acre is 43,560 square feet, which equals 4,840 square yards or about 4,047 square meters. To convert square feet to acres, divide by 43,560 — a 10,000 sq ft lot is about 0.23 acres.
How we built this calculator: results use the standard volume, area, and coverage formulas shown on this page, with typical U.S. material densities, bag yields, and waste factors that you can override. Written and checked by the YardsCalculator editorial team. Last reviewed: October 2026.