Square Meter Calculator
A square meter is the area of a square one meter on each side, and working out how many of them fit in a space is length times width. The calculator takes the two measurements in meters, centimeters, millimeters, feet, or inches, in any mix, adds up as many rooms as you need, and gives the total in square meters (m2) with square feet alongside.
How to calculate square meters
Square meters = length in meters x width in meters
A room 4.2 meters long and 3.6 meters wide is 4.2 x 3.6 = 15.12 m2. That's the whole method for any rectangular space. NIST describes the unit exactly that way: the square meter is the SI unit of area, a square that is 1 m on each side.
Three steps, every time:
- Measure the length and width.
- Convert both to meters if they aren't already.
- Multiply them.
The conversion in step two is where most mistakes happen, so here it is in full.
Working from centimeters, millimeters, or feet
Centimeters. Convert each side to meters first by dividing by 100, then multiply. 420 cm x 360 cm is 4.2 m x 3.6 m, which is 15.12 m2.
If you've already multiplied the centimeters, you have square centimeters, and there are 10,000 of those in a square meter, not 100. 420 x 360 = 151,200 cm2, divided by 10,000 is 15.12 m2. Dividing by 100 here is the classic mistake, and it gives an answer 100 times too big.
Millimeters. Divide each side by 1,000 before multiplying, or divide the finished square millimeters by 1,000,000. Architectural drawings and kitchen plans are often dimensioned in millimeters, so this comes up more than you'd expect.
Feet. Either convert each side to meters (1 foot is 0.3048 m) and multiply, or multiply in feet and convert the square footage by 0.092903. A 12 by 15 foot room is 180 square feet, which is 16.72 m2, and 3.66 m x 4.57 m gives the same answer. The square feet to square meters converter has a full table if you're converting a finished number.
| Unit you measured in | Convert each side to meters | Or convert the finished area |
|---|---|---|
| Centimeters | Divide by 100 | cm2 divided by 10,000 |
| Millimeters | Divide by 1,000 | mm2 divided by 1,000,000 |
| Feet | Multiply by 0.3048 | sq ft x 0.092903 |
| Inches | Multiply by 0.0254 | sq in divided by 1,550 |
Room sizes in square meters
| Room dimensions | Square meters | Square feet |
|---|---|---|
| 2.5 x 3 m | 7.5 m2 | 80.7 sq ft |
| 3 x 3 m | 9 m2 | 96.9 sq ft |
| 3 x 4 m | 12 m2 | 129.2 sq ft |
| 3.5 x 4 m | 14 m2 | 150.7 sq ft |
| 4 x 4 m | 16 m2 | 172.2 sq ft |
| 4 x 5 m | 20 m2 | 215.3 sq ft |
| 5 x 6 m | 30 m2 | 322.9 sq ft |
| 6 x 8 m | 48 m2 | 516.7 sq ft |
| 8 x 10 m | 80 m2 | 861.1 sq ft |
| 10 x 10 m | 100 m2 | 1,076.4 sq ft |
Shapes that aren't rectangles
L-shaped rooms. Split the room into two rectangles, work out each, and add them. A main area of 3.2 by 2.8 m (8.96 m2) plus an alcove of 2.1 by 1.5 m (3.15 m2) is 12.11 m2. Add each piece as its own row in the calculator and it totals them.
Triangles. Base times height divided by two. A triangular corner with a 4 m base and a 3 m height is 6 m2.
Circles. Pi times the radius squared. A round patio 3 m across has a 1.5 m radius, so 3.1416 x 1.5 x 1.5 = 7.07 m2.
Anything else. Break it into rectangles, triangles, and part circles, or use the offset method for a curved edge. The irregular shape calculator covers both, and the circle and triangle calculators handle those shapes on their own.
Worked examples
Flooring. A bedroom 3.6 by 4.2 m is 15.12 m2. Add 10 percent for cutting waste and order about 16.6 m2. Flooring sold in the US is often boxed in square feet, so that's about 179 sq ft.
Paint. Walls are length times height. A wall 5.5 m long and 2.6 m high is 14.3 m2, minus a 2.0 by 0.9 m door (1.8 m2), leaving 12.5 m2 to paint. The wall calculator repeats that for a whole room.
Tiles. A shower wall 2.4 by 3.0 m is 7.2 m2. Tile is almost always sold by the square meter outside the US, so that's the number to take to the shop, plus waste.
Common mistakes
Dividing square centimeters by 100. It's 10,000. A square meter is 100 cm by 100 cm.
Mixing units in one multiplication. Meters times centimeters gives nothing useful. Convert first, or set the unit on each side in the calculator.
Multiplying more than two sides. Area is two dimensions. Multiplying by a third gives volume in cubic meters, which is what you'd want for concrete, not for flooring.
Rounding each measurement before multiplying. Keep the decimals until the end. 3.64 x 4.18 is 15.22 m2, while 3.6 x 4.2 is 15.12. On a big floor that difference becomes a box of tile.
Frequently asked questions
How do I calculate square meters?
Multiply the length in meters by the width in meters. A room 4 m by 5 m is 20 square meters. If you measured in centimeters, divide each side by 100 first, or divide the result by 10,000.
How do I calculate square meters of a room?
Measure the longest length and width of the floor in meters and multiply them. For an L-shaped room, split it into two rectangles, calculate each, and add the two areas together.
How many square centimeters are in a square meter?
10,000. A square meter is 100 cm on each side, and 100 x 100 is 10,000. That's why converting square centimeters to square meters means dividing by 10,000, not 100.
How do I calculate square meters from feet?
Either convert each side to meters by multiplying by 0.3048 and then multiply the two, or multiply in feet to get square feet and then multiply by 0.092903. Both give the same answer.
What is m2?
It's the symbol for the square meter, the standard unit of area in the metric system. You'll also see it written as sq m, sqm, or m with a superscript 2. They all mean the same unit.
How big is one square meter?
A square 1 meter on each side, a little over 3 feet 3 inches by 3 feet 3 inches. It's almost 11 square feet, or roughly the floor space a single person occupies standing with room to turn around.
How many square meters is a hectare?
10,000 square meters, a square 100 meters on each side. It's about 2.47 acres.
Sources
Related tools
Square feet to square meters | Square meters to square feet | Rectangle calculator | Irregular shape calculator