Square Meter Calculator

Q: How many square meters does one liter of paint cover?

Most wall paint covers about 10 to 12 square meters per liter for one coat. Rough walls, bare plaster, and dark colors soak up more, so coverage can drop to 6 to 8 m² per liter. Most jobs need two coats, so double the paint. For 30 m² of wall with two coats, you need about 60 m² of coverage, or roughly 5 to 6 liters.

Q: How many square meters are in an acre and a hectare?

One acre = 4,046.86 square meters . One hectare = 10,000 square meters , which is a square 100 m on each side. One hectare is about 2.47 acres. These units are used for land, farms, and big lots instead of square meters.

Q: How big is 20 square meters?

20 square meters is about 215 square feet . It is the size of a room 5 m by 4 m, or about 4.5 m by 4.5 m. That is a normal size for a large bedroom, a small studio flat, or a one-car garage floor.

Q: How do I find the area of a circle if I only know the radius?

Use A = π × r² . Square the radius, then multiply by 3.14159. Example: a circle with a 2 m radius is 2 × 2 = 4, then 4 × 3.14159 = 12.57 m² . If you have the diameter instead, cut it in half first to get the radius.

Square Meter Calculator

Introduction

The Square Meter Calculator finds the area of a space in square meters. Pick a shape, type in your measurements, and the area appears. It works for rooms, floors, walls, gardens, tiles, paint jobs, and more.

You can choose from eight shapes: rectangle, square, circle, triangle, pentagon, hexagon, octagon, and ellipse. Enter your numbers in millimeters, centimeters, meters, inches, feet, or yards. The tool converts the units for you.

Your answer shows up in square meters, square centimeters, square feet, square yards, and square inches all at once. A diagram shows the shape you picked so you know which side is which.

There are extra settings too. Add a border to find the inner area or the frame area. Multiply by the number of rooms or panels you have. Add a waste percent so you buy enough material. Put in a price to see what the job will cost.

Each answer comes with a step-by-step solution, so you can see the math and check the work yourself.

How to use our Square Meter Calculator

Pick your shape, type in your measurements, and the square meter calculator shows the area in sq m, sq cm, sq ft, sq yd, and sq in, plus waste, totals, and cost.

Shape: Choose the shape of your space, like a rectangle, square, circle, triangle, pentagon, hexagon, octagon, or ellipse. Only the boxes you need will show up.

Primary result unit: Pick the unit for the main answer, such as sq m or sq ft. This unit is also used for the totals and the chart.

Length: Type the longer side of your rectangle and pick its unit (mm, cm, m, in, ft, or yd).

Width: Type the shorter side of your rectangle and pick its unit.

Side Length: For a square, pentagon, hexagon, or octagon, type the length of one side. All sides are equal.

Diameter: For a circle, type the full width across the middle, not the radius.

Side A, Side B, and Side C: For a triangle, type all three side lengths. The sides must be able to form a real triangle.

Semi-axis a and Semi-axis b: For an ellipse, type half the long axis and half the short axis, measured from the center to the edge.

Include Border Calculation: Turn this on if your space has a frame or border strip around the edge.

Border Width: Type how wide the border is, measured inward from the outside edge, then pick its unit.

Apply quantity, waste & price to: Choose if the totals use the whole area, just the inside area, or just the border area.

Number of identical areas: Type how many rooms, panels, or pieces are the same size. Use the plus and minus buttons to change it fast.

Add Waste / Overage (%): Type extra percent for cuts and breakage. Most tiling jobs use 5% to 15%.

Currency symbol: Pick the money sign you want to see in the cost result.

Price per unit area: Type what you pay for each unit of area and pick that unit, like per sq m or per sq ft. Leave it blank or at 0 to hide the cost.

Calculate and Reset: Click Calculate to see your area, chart, and step-by-step math. Click Reset to start over with the default values.

What Is a Square Meter?

A square meter (m²) is a unit of area. It is the space inside a square that is 1 meter long on every side. Area tells you how much flat space a surface covers, like a floor, a wall, a yard, or a piece of fabric. People use square meters to buy tile, carpet, paint, turf, wallpaper, and flooring.

How to Calculate Square Meters

For a rectangle or square room, measure the length and the width in meters, then multiply them:

Area = Length × Width

A room that is 5 m long and 4 m wide is 5 × 4 = 20 square meters. If you measure in feet, inches, or centimeters, change the numbers to meters first, or let the calculator do it for you.

Area Formulas for Common Shapes

Square: A = s × s
Rectangle: A = L × W
Circle: A = π × (d ÷ 2)²
Triangle (3 sides): Heron's formula, A = √[s(s−a)(s−b)(s−c)], where s is half the perimeter
Regular pentagon: A = s² × √(25 + 10√5) ÷ 4
Regular hexagon: A = (3√3 ÷ 2) × s²
Regular octagon: A = 2(1 + √2) × s²
Ellipse: A = π × a × b (a and b are the half-axes)

Square Meter Conversions

1 m² = 10,000 cm²
1 m² = 1,000,000 mm²
1 m² = 10.7639 ft²
1 m² = 1.19599 yd²
1 m² = 1,550 in²
1 ft² = 0.092903 m²

Borders and Inner Area

A border is a strip around the edge of a shape, like a tile trim, a grass edge, or a picture frame. The border width is measured inward from the outside edge. The space left in the middle is the inner area. Border area = total area − inner area. This helps when you buy one material for the middle and a different one for the edge.

Why Add Waste?

You almost always need a little extra material. Tiles break, cuts leave scraps, and patterns must line up. Most people add 5% to 15% extra. Use about 10% for simple square rooms and 15% or more for diagonal layouts or rooms with many corners.

Tips for Good Measurements

Measure at floor level, not at eye level, for rooms.
Measure twice and write the numbers down.
Split odd-shaped rooms into smaller rectangles, find each area, then add them.
Use the diameter (full width) for circles, not the radius.
Round up when you buy, since that costs less than a second trip.

Formulas used

Rectangle area

A = L \times W

Circle area from diameter

A = \pi \left(\frac{d}{2}\right)^2

Triangle area (Heron's formula)

s = \frac{a+b+c}{2}, \quad A = \sqrt{s(s-a)(s-b)(s-c)}

Regular polygon areas (pentagon, hexagon, octagon)

A_5 = \frac{s^2\sqrt{25+10\sqrt{5}}}{4}, \quad A_6 = \frac{3\sqrt{3}}{2}s^2, \quad A_8 = 2\left(1+\sqrt{2}\right)s^2

Ellipse area

A = \pi a b

Inner and border area after a border of width t

A_{\text{inner}} = A\left(\frac{a_p - t}{a_p}\right)^2, \quad A_{\text{border}} = A - A_{\text{inner}}

Total area with quantity and waste allowance

A_{\text{buy}} = A_{\text{basis}} \times Q \times \left(1 + \frac{w}{100}\right)

Estimated cost

\text{Cost} = A_{\text{buy}} \times \frac{P}{k_{\text{unit}}}

Frequently asked questions

How many square meters is a 12 foot by 12 foot room?

A 12 ft by 12 ft room is 144 square feet. One square foot equals 0.092903 square meters, so:

144 × 0.092903 = about 13.38 square meters

A quick check: divide square feet by 10.764. That gives the same answer.

Is a square meter the same as a meter squared?

Yes. "Square meter," "meter squared," "sq m," "sqm," and "m²" all mean the same unit of area.

Watch out for one trap: "3 meters squared" can be read as a square with 3 m sides, which is 9 m². That is not the same as "3 square meters." Say the number first, like "3 square meters," to stay clear.

How do I work out the square meters of an L-shaped room?

Split the room into two rectangles. Draw a line across the room where the wall steps in or out.

Measure the length and width of each rectangle.
Multiply length × width for each one.
Add the two areas together.

Example: 5 m × 4 m = 20 m², plus 3 m × 2 m = 6 m². Total = 26 m².

How many square meters does one liter of paint cover?

Most wall paint covers about 10 to 12 square meters per liter for one coat. Rough walls, bare plaster, and dark colors soak up more, so coverage can drop to 6 to 8 m² per liter.

Most jobs need two coats, so double the paint. For 30 m² of wall with two coats, you need about 60 m² of coverage, or roughly 5 to 6 liters.

How many tiles do I need for one square meter?

Divide 1 by the area of one tile in square meters.

10 × 10 cm tile = 0.01 m² → 100 tiles per m²
20 × 20 cm tile = 0.04 m² → 25 tiles per m²
30 × 30 cm tile = 0.09 m² → about 11.1 tiles per m²
60 × 60 cm tile = 0.36 m² → about 2.8 tiles per m²

Then add 10% extra for cuts and breakage.

What is the difference between square meters and linear meters?

A linear meter measures length only, in one direction. A square meter measures area, which is length times width.

Carpet and vinyl are often sold by the linear meter off a roll of a set width. A 4 m wide roll cut to 3 linear meters gives 4 × 3 = 12 square meters of material.

How many square meters are in an acre and a hectare?

One acre = 4,046.86 square meters.

One hectare = 10,000 square meters, which is a square 100 m on each side.

One hectare is about 2.47 acres. These units are used for land, farms, and big lots instead of square meters.

How do I calculate the square meters of a wall for paint or wallpaper?

Multiply the wall height by the wall width. Do this for each wall, then add them up.

Example: a wall 4 m wide and 2.5 m high is 4 × 2.5 = 10 m².

For paint, you can leave doors and windows in as a safety margin. For wallpaper, subtract big openings: a door is about 1.6 m² and a window about 1.5 m².

How big is 20 square meters?

20 square meters is about 215 square feet. It is the size of a room 5 m by 4 m, or about 4.5 m by 4.5 m.

That is a normal size for a large bedroom, a small studio flat, or a one-car garage floor.

How do I find the area of a circle if I only know the radius?

Use A = π × r². Square the radius, then multiply by 3.14159.

Example: a circle with a 2 m radius is 2 × 2 = 4, then 4 × 3.14159 = 12.57 m².

If you have the diameter instead, cut it in half first to get the radius.

Do I subtract doors, closets, or cabinets when measuring floor area?

Measure the floor you will actually cover.

Add closet floors and door openings if flooring runs into them.
Subtract built-in cabinets, islands, and fixed units that sit on the subfloor.
Do not subtract furniture you can move.

When in doubt, leave it in. Extra material costs less than a second trip to the store.

Why does doubling a room's sides make the area four times bigger?

Because area grows in two directions at once. If both the length and the width double, you multiply the area by 2 × 2 = 4.

Example: 3 m × 3 m = 9 m². Double it to 6 m × 6 m = 36 m², which is four times as big.

This is why a small size change can raise your material cost a lot.

How do I measure the square meters of a sloped roof?

Do not use the flat footprint of the house, because a slope covers more surface than the ground under it.

Measure the slope length from the edge up to the ridge, then multiply by the roof width. Do this for each roof face and add them.

If you can only measure the ground area, multiply it by a pitch factor: about 1.08 for a gentle roof, 1.12 for medium, and 1.25 or more for a steep roof.

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