A square footage calculator finds area by multiplying length by width for each room and adding the results, so a 15 ft by 20 ft room is 300 square feet. This free square footage calculator adds several rooms, triangles, circles and L-shapes, shows square meters too, and works out the cost or the price per square foot.
Quick answer: Square footage = length × width, in feet. A room 18 ft long and 15 ft wide is 18 × 15 = 270 sq ft. For several rooms, add the areas: 270 + 168 + 156 = 594 sq ft. To get square meters, multiply square feet by 0.0929, so 594 sq ft is 55.2 m².
How to use this square footage calculator
Type one room or shape per line in the box. The total updates as you type, and the table lists the area of every line with its share of the total. Choose Feet or Meters at the top, and add a price if you want a cost.
- Measure each room from wall to wall in feet (or meters). Write the length, an x, then the width, such as Kitchen 12×14.
- Add triangles, circles and cut-outs on their own lines using the shorthand in the table below.
- Read the total in square feet and square meters, and check the table for each room.
- Optional: enter a price per square foot to get a cost, or a total price to get the price per square foot.
| Type this | It means | Example and result |
|---|---|---|
| 18×15 | Rectangle, length × width | 18 × 15 = 270 sq ft |
| t 6×4 | Triangle, base × height ÷ 2 | 6 × 4 ÷ 2 = 12 sq ft |
| d6 | Circle with a diameter of 6 | π × 3² = 28.27 sq ft |
| r3 | Circle with a radius of 3 | π × 3² = 28.27 sq ft |
| -3×2 | Subtract a rectangle (a closet, stairwell or cut-out) | takes away 6 sq ft |
| 12’6″ x 8′ | Feet and inches are understood | 12.5 × 8 = 100 sq ft |
How is square footage calculated?
Square footage is the area of a flat surface measured in square feet, where one square foot is a square that is 1 ft on each side. The formula depends on the shape. Break the floor into simple shapes, find each area and add them up; the square footage calculator does exactly that and prints every step.
- Rectangle or square: length × width.
- Triangle: base × height ÷ 2.
- Circle: π × radius², with π ≈ 3.14159.
- L-shape: split it into two rectangles and add them.
- Trapezoid: (top + bottom) ÷ 2 × height.
Example 1: a home with seven spaces
This is the example the calculator opens with. Each line is a room or a shape, and the areas add up to 792.3 sq ft, which is 73.6 square meters.
| Room or shape | Working | Square feet |
|---|---|---|
| Living room | 18 × 15 | 270 |
| Kitchen | 12 × 14 | 168 |
| Bedroom 1 | 13 × 12 | 156 |
| Bedroom 2 | 11 × 10 | 110 |
| Bathroom | 8 × 6 | 48 |
| Hall (triangle) | 6 × 4 ÷ 2 | 12 |
| Bay window nook (circle) | π × 3² | 28.27 |
| Total | 792.3 |
Example 2: an L-shaped room
An L-shaped living area is 20 ft by 12 ft with an extension 8 ft by 6 ft. Split it into two rectangles: 20 × 12 = 240 sq ft and 8 × 6 = 48 sq ft. The total is 240 + 48 = 288 sq ft, or 26.8 m². In the calculator, type 20×12 on one line and 8×6 on the next. You can also type the full rectangle and subtract the missing corner with a minus line.
Example 3: metric
A room measures 5 m by 4 m. Switch the units to meters: 5 × 4 = 20 m². To see square feet, divide by 0.09290304, which gives 215.3 sq ft. The National Institute of Standards and Technology lists one square foot as exactly 0.092 903 04 square meters.
Square footage calculator for multiple rooms
To find the square footage of a house or apartment, measure every room separately and add them with the square footage calculator. Giving each room its own line keeps the work checkable, and the table shows which rooms take the most space. Write closets and hallways on their own lines, so you can leave them out when you only want living space.
Two habits prevent most errors. First, measure each room at its widest points and note any alcoves. Second, do not measure the whole outline and then add rooms on top, because that counts the same floor twice.
Square footage calculator irregular shape: split it into simple shapes
For an odd-shaped room, an L-shaped yard or a wedge-shaped lot, split the outline into rectangles and triangles, find each area and add them. If a corner is cut off, type the full rectangle and subtract the corner with a leading minus. Searching for a square footage calculator irregular shape layout? This method works for any straight-sided outline.
If you know the three side lengths of a triangle but not its height, use Heron’s formula: with sides a, b and c, let s = (a + b + c) ÷ 2, and the area is √(s × (s − a) × (s − b) × (s − c)). A triangle with sides 13, 14 and 15 has s = 21 and an area of √(21 × 8 × 7 × 6) = 84 sq ft. An irregular four-sided lot can be cut along one diagonal into two such triangles.
Square feet to square meters and other conversions
To convert square feet to square meters, multiply by 0.09290304. To go back, divide by the same number, or multiply by 10.7639. One square yard is 9 square feet, and one acre is 43,560 square feet.
| Square feet | Square meters | Square yards |
|---|---|---|
| 100 | 9.3 | 11.1 |
| 150 | 13.9 | 16.7 |
| 200 | 18.6 | 22.2 |
| 300 | 27.9 | 33.3 |
| 500 | 46.5 | 55.6 |
| 750 | 69.7 | 83.3 |
| 1,000 | 92.9 | 111.1 |
| 1,500 | 139.4 | 166.7 |
| 2,000 | 185.8 | 222.2 |
| 2,500 | 232.3 | 277.8 |
| 3,000 | 278.7 | 333.3 |
| Square meters | Square feet |
|---|---|
| 10 | 107.6 |
| 20 | 215.3 |
| 30 | 322.9 |
| 50 | 538.2 |
| 75 | 807.3 |
| 100 | 1,076.4 |
| 150 | 1,614.6 |
| 200 | 2,152.8 |
| 250 | 2,691.0 |
Common room sizes in square feet
These are sizes people often measure, with the area the square footage calculator gives for each. They are examples, not building standards, so measure your own space.
| Size | Square feet | Square meters | Typical use |
|---|---|---|---|
| 10 × 10 ft | 100 | 9.3 | Small bedroom or home office |
| 10 × 12 ft | 120 | 11.1 | Bedroom or nursery |
| 12 × 12 ft | 144 | 13.4 | Bedroom or dining room |
| 12 × 14 ft | 168 | 15.6 | Kitchen or large bedroom |
| 12 × 16 ft | 192 | 17.8 | Primary bedroom |
| 14 × 16 ft | 224 | 20.8 | Living room |
| 15 × 20 ft | 300 | 27.9 | Large living room |
| 16 × 20 ft | 320 | 29.7 | Great room |
| 20 × 20 ft | 400 | 37.2 | One-car-plus garage or studio |
| 20 × 24 ft | 480 | 44.6 | Two-car garage |
Price per square foot and total cost
Price per square foot is the total price divided by the area, and the cost of a job is the area times the price per square foot. A house that sells for $350,000 with 2,000 sq ft is $350,000 ÷ 2,000 = $175 per square foot. A room of 352 sq ft with flooring at $3.50 per square foot costs 352 × 3.50 = $1,232. Installers often suggest ordering 5% to 10% extra for cuts and waste, so add that to the area.
Cost by area and price per square foot
| Area | $2 per sq ft | $4 per sq ft | $6 per sq ft | $8 per sq ft | $10 per sq ft |
|---|---|---|---|---|---|
| 100 sq ft | $200 | $400 | $600 | $800 | $1,000 |
| 250 sq ft | $500 | $1,000 | $1,500 | $2,000 | $2,500 |
| 500 sq ft | $1,000 | $2,000 | $3,000 | $4,000 | $5,000 |
| 1,000 sq ft | $2,000 | $4,000 | $6,000 | $8,000 | $10,000 |
| 1,500 sq ft | $3,000 | $6,000 | $9,000 | $12,000 | $15,000 |
| 2,000 sq ft | $4,000 | $8,000 | $12,000 | $16,000 | $20,000 |
The price per square foot of a home is a handy comparison, but it hides differences in land, condition and which spaces were counted. Compare it only between homes measured the same way.
How real estate counts the square footage of a house
Real estate measurements follow rules, and they differ from simply adding the rooms you can walk into. In the United States, the ANSI Z765 standard, Square Footage: Method for Calculating, is the national method for single-family homes. Home Innovation Research Labs publishes it and says the 2021 version is approved and currently in use.
McKissock Learning summarizes the main rules for appraisers: measure to the outside walls, report to the nearest whole square foot, count only finished areas with a ceiling at least 7 feet high (for a sloped ceiling, at least half of the room at 7 feet, and no area under 5 feet), and report a basement as below-grade area rather than living area. Fannie Mae and Freddie Mac have both adopted the standard for one-unit homes, according to the same summary.
| Space | Usually counted in a home’s living area? | Why |
|---|---|---|
| Finished rooms above ground, 7 ft ceilings | Yes | Finished above-grade area |
| Finished basement | No, listed separately | Below-grade area is reported on its own line |
| Garage | No | Not finished living space |
| Sloped-ceiling attic room | Partly | Needs enough 7 ft height; nothing under 5 ft counts |
| Stairs | Yes, on the floor they descend from | ANSI counts the stairs with that floor |
With a square footage calculator you get the sum of the spaces you measured. That is why a listing can say 2,000 sq ft while your own room-by-room total is lower: walls are included in the outside measurement. For flooring, paint or furniture, use the inside measurements this square footage calculator adds up. For comparing homes, use the listed figure. Always check the rules used in your area, and ask the agent or appraiser how the number was measured.
Square footage for the US, Canada, the UK and Australia
Square feet are the usual unit for floor area in the United States. Most other countries, including the UK, Canada and Australia, officially use square meters, although many property listings in those places show both. Switch the units in the calculator to match your measuring tape, and read the other unit from the results. The conversion is exact: 1 sq ft = 0.09290304 m².
Common mistakes when you calculate square footage
- Mixing units. Feet and inches in one number give wrong answers, unless you write 12’6″ or 12.5. Convert inches to feet by dividing by 12.
- Using the wrong shape formula. A triangle is half of a rectangle, so forgetting the ÷ 2 doubles the answer.
- Counting overlaps twice. Split an L-shape into two rectangles that touch but do not overlap.
- Using the diameter as the radius. A circle with a 6 ft diameter has a radius of 3 ft, and the area is π × 3², not π × 6².
- Confusing square feet with feet. A room 10 ft by 10 ft is 100 sq ft, not 20 ft.
Real-life uses with numbers
Flooring. A bedroom 13 × 12 ft is 156 sq ft. With 10% extra for waste you buy 172 sq ft of planks. Paint. Walls are measured in square feet too: a wall 12 ft wide and 8 ft high is 96 sq ft, minus a window of 3 × 4 ft = 12 sq ft, leaves 84 sq ft to paint.
Garden. A lawn 40 × 25 ft is 1,000 sq ft, so a product labeled for 5,000 sq ft covers it five times. Renting. If rent is $1,800 for 900 sq ft, you pay $2.00 per square foot per month.
Questions people ask about square footage
How do I calculate the square footage of a room?
Measure the length and the width in feet and multiply them. A room 14 ft by 16 ft is 14 × 16 = 224 sq ft. For a room that is not a rectangle, split it into rectangles and triangles and add the areas.
How do I find the square footage of a house?
Measure each finished room, add the areas, and decide whether to include hallways and closets. Listings use the outside-wall method, so a listed figure is usually larger than a sum of interior rooms.
Frequently asked questions
10 quick answers
How many square feet is a 12 by 12 room?
A 12 by 12 room is 144 square feet (12 × 12), which is 13.4 square meters. A 10 by 10 room is 100 sq ft and a 20 by 20 room is 400 sq ft.
How do I convert square feet to square meters?
Multiply the square feet by 0.09290304. For example, 1,000 sq ft × 0.0929 = 92.9 m². To go the other way, divide square meters by 0.0929.
How many square feet are in an acre?
One acre is 43,560 square feet. A lot 200 ft by 218 ft is close to one acre, at 43,600 sq ft.
How many square feet are in a square yard?
A square yard is 3 ft by 3 ft, so it has 9 square feet. To convert square feet to square yards, divide by 9.
How do I calculate the square footage of an L-shaped room?
Split the L into two rectangles, find length × width for each and add them. Or find the big rectangle and subtract the missing corner. The calculator takes both approaches.
How do I calculate square footage of an irregular shape?
Divide the shape into rectangles, triangles and circles, find each area and add them. Subtract any cut-outs. Triangles are base × height ÷ 2.
How do I calculate square footage for multiple rooms?
Calculate each room as length × width and add them. In this square footage calculator, put each room on its own line and the total appears at the top, with a table of every room.
How do I calculate price per square foot?
Divide the total price by the number of square feet. A $240,000 home with 1,600 sq ft costs $240,000 ÷ 1,600 = $150 per square foot.
Do walls count in square footage?
In the United States ANSI Z765 measures a home to the outside walls, so walls are included in the listed figure. For flooring or paint, measure inside the walls.
Is a circle measured in square feet too?
Yes. Find the area as π × radius² in square feet. A circular patio 10 ft across has a radius of 5 ft and an area of 78.5 sq ft.
Related calculators
- Perimeter and area calculator for the area and perimeter of a single shape
- Flooring calculator for how much flooring to buy
- Paint calculator for walls and ceilings
- Mulch calculator for beds, gravel and topsoil
- Unit converter for area units
- All calculators
Sources and further reading
- Home Innovation Research Labs: ANSI Z765 Square Footage standard (2021 version in use)
- McKissock Learning: ANSI measuring standard summary (outside walls, 7 ft ceilings, below-grade rules)
- NIST Guide to the SI, Appendix B (square foot to square meter)
- Wikipedia: Square foot
Measurement rules differ by place and purpose, so check the rule that applies to your sale, rental or project. Last updated: October 2026.