Square metre calculator
Pick a shape for each room, type its measurements in metres and get the total floor area in square metres and house squares.
Total floor area
- Total floor area
- 31.88 m²
- Square feet
- 343.15 sq ft
- House squares
- 3.43 squares1 square = 100 sq ft = 9.290304 m²
Estimate only. Check product labels and the building rules in your state or territory before you buy or build.
Quick answer
Square metres are length × width in metres for a rectangular room. For any other floor, split it into rectangles, triangles, circles or trapeziums, work out each part and add them up: a 5 × 4 m room (20 m²) plus a 3.6 × 3.3 m room (11.88 m²) is 31.88 m². One house square is 100 sq ft, or 9.290304 m², so 31.88 m² is 3.43 squares.
How to use the square metre calculator
- Choose how you measured: metres, centimetres or millimetres. If an old plan gives feet and inches, switch to Imperial and pick Feet and inches. Numbers you have already typed are converted.
- For each room or part of a room, pick its shape and type the measurements. The drawing shows the shape you entered, and its area appears next to it.
- Add an area for every room or section of floor. Set an area to Subtract for anything you will not cover, such as a kitchen island bench or a built-in robe.
- Read the total in square metres, with square feet and house squares below it. An area with a missing measurement is left out of the total until you fill it in.
How do you work out square metres?
Multiply the length by the width, both in metres: a room 5 m long and 4 m wide is 5 × 4 = 20 m². For a floor that is not a rectangle, split it into simple shapes, work out each one with the formulas below and add the results. Subtract anything you will not cover.
If you measured in millimetres, divide the result by 1,000,000 to get square metres: 3600 × 3300 mm is 11,880,000 mm², or 11.88 m². A foot is exactly 0.3048 m, so a square foot is 0.09290304 m² and a house square of 100 sq ft is 9.290304 m².
rectangle = length × widthL-shape = overall length × overall width − missing corner length × missing corner widthtriangle = base × height ÷ 2triangle from sides a, b, c: s = (a + b + c) ÷ 2, area = √(s × (s − a) × (s − b) × (s − c))circle = π × (diameter ÷ 2)²trapezium = (parallel side 1 + parallel side 2) ÷ 2 × distance between themsquares = square metres ÷ 9.290304square feet = square metres ÷ 0.09290304House squares to square metres
One square is 100 sq ft. Each value below is squares × 9.290304, rounded to two decimals.
| Squares | Square feet | Square metres |
|---|---|---|
| 15 | 1,500 | 139.35 |
| 18 | 1,800 | 167.23 |
| 20 | 2,000 | 185.81 |
| 22 | 2,200 | 204.39 |
| 25 | 2,500 | 232.26 |
| 28 | 2,800 | 260.13 |
| 30 | 3,000 | 278.71 |
| 35 | 3,500 | 325.16 |
| 40 | 4,000 | 371.61 |
Worked examples
An L-shaped open-plan living area
The living, kitchen and dining area is 8.4 m along its longest wall and 6 m across, with a 3 m × 2.4 m corner taken up by the laundry. Choose L-shape and enter 8.4, 6, 3 and 2.4.
The full rectangle is 8.4 × 6 = 50.4 m² and the missing corner is 3 × 2.4 = 7.2 m², so the area is 50.4 − 7.2 = 43.2 m². That is 4.65 squares, or 465 sq ft.
A kitchen floor around an island bench
The kitchen is 4.2 m × 3.6 m, which is 15.12 m². The new tiles will not go under the 2.4 m × 0.9 m island bench, so add the bench as a second area set to Subtract: 2.16 m².
The floor to tile is 15.12 − 2.16 = 12.96 m². Order tiles for that area plus a waste allowance for cuts, not for the whole room.
How big is an average new house in Australia’s capital cities?
New private sector houses approved in Sydney, Melbourne, Brisbane, Adelaide and Perth averaged 248 m² of floor area in 2019-20, or about 26.69 squares. The Australian Bureau of Statistics reports that the average was 234 m² in 2005-06, and 2019-20 is the latest year in its article.
Blocks shrank over the same years: the average site area of those new houses fell from 602 m² to 467 m². Squares describe the size of a house, not of the land, so block sizes are given in square metres.
How do I measure a room that is not a rectangle?
Split it into rectangles first, then use a triangle, trapezium or circle only for the parts that are left. Measure wall to wall at floor level and write each length down as you go. An L-shaped room is easiest as one big rectangle minus the missing corner, which is what the L-shape option does.
Where you cannot measure the height of a triangle at a right angle, measure its three sides and use the three-sides option. For a round room or a curved garden bed, measure the diameter straight across through the centre. A builder’s plan may count area differently from a room measured wall to wall, so check how the plan defines it before you compare the two.
Common questions
How many square metres is a square?
One square is 9.290304 m², because a square is 100 sq ft and a square foot is exactly 0.09290304 m². A 25-square house is 25 × 9.290304 = 232.26 m², and a 30-square house is 278.71 m². Squares describe the size of a house, not land. Ask the builder what a quoted number of squares includes before you compare two homes.
How do I convert square metres to squares?
Divide square metres by 9.290304. A 200 m² home is 200 ÷ 9.290304 = 21.53 squares, and a 248 m² home is 26.69 squares. Dividing by 9.29 gives almost the same answer for a house-sized area. To go the other way, multiply the number of squares by 9.290304.
How do I work out the square metres of a room?
Multiply the length by the width in metres. A room 5 m by 4 m is 5 × 4 = 20 m². If you measured in millimetres, convert first: 3600 mm is 3.6 m. If the room is not a rectangle, split it into rectangles and other simple shapes, work out each one and add them together.
How do I work out the area of an L-shaped room?
Multiply the overall length by the overall width, then subtract the missing corner. An area 8.4 m by 6 m with a 3 m by 2.4 m corner cut out is 50.4 − 7.2 = 43.2 m². You can also split the L into two rectangles and add them: 5.4 × 6 + 3 × 3.6 = 32.4 + 10.8 = 43.2 m², the same answer.
How do I convert square metres to square feet?
Divide square metres by 0.09290304, or multiply by 10.764 for a close answer. The factor is exact because a foot is defined as exactly 0.3048 m, and 0.3048 × 0.3048 = 0.09290304. So 20 m² is 215.28 sq ft, and 31.88 m² is 343.15 sq ft.
How do I work out the area of a circle?
Multiply π by the radius squared, where the radius is half the diameter. A round garden bed 3 m across has a radius of 1.5 m, so its area is 3.1416 × 1.5 × 1.5 = 7.07 m². For a half circle, work out the full circle and divide by 2. Measure the diameter through the centre at its widest point.
Sources
- Henley Homes, Calculating home squares, lot sizes, and floor plan measurements (checked 19 October 2026)One square is 100 sq ft; 9.290304 m² in one square; squares measure house size, not land size.
- Australian Bureau of Statistics, Australians building houses on smaller blocks (8 September 2020) (checked 19 October 2026)Average floor area of new private sector houses approved in Sydney, Melbourne, Brisbane, Adelaide and Perth: 234 m² in 2005-06, 248 m² in 2019-20; average site area 602 m² to 467 m².
- National Institute of Standards and Technology (NIST), U.S. Survey Foot (checked 19 October 2026)The international foot is exactly 0.3048 m.
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