Square Metre Calculator: Work Out Any Area in m²
Work out the area of a room, floor, wall or garden in square metres. Add rectangles, triangles and circles together for L-shaped rooms and odd shapes, take away the parts you’re not covering, and see square feet alongside.
No sign-up required. Free to use, with every formula shown on this page. Last reviewed October 2026.
Work out your area
Square Metre Calculator
Work out the area of a room, floor, wall or garden in square metres (m²). Add rectangles, triangles and circles together, take away the bits you're not covering, and see square feet alongside.
1 How you measured
The result is always shown in both square metres and square feet.
2 Your areas
An L-shaped room is two rectangles. Use "Take away" for things you're not covering, like a kitchen island, a hearth or a pond.
3 Extra for waste (optional)
For flooring, tiles or turf, buy extra for cuts: about 5% for simple rooms, 10% for most, 15% for diagonal layouts or lots of corners.
4 Price (optional)
For flooring, carpet, turf or paving. Leave empty to skip.
Total area
0 m²
Square feet
0 ft²
Square yards
0 yd²
Perimeter
–
Area by area
| Area | Size | m² |
|---|
What's next?
How it's worked out: rectangle = length × width; triangle = base × height ÷ 2; circle = π × (diameter ÷ 2)², and half of that for a half circle; trapezium = (side A + side B) ÷ 2 × the distance between them. Areas marked "Take away" are subtracted. 1 m² = ft² = yd²; 1 ft = m.
Estimates only. Measure at the widest points and round up: rooms are rarely perfectly square. Check the quantity with your supplier before you buy.
How it works
How to work out square metres
Area is how much flat surface something covers. For most rooms it’s just length × width; for anything else, split it into simple shapes and add them up. The sources and assumptions behind it are on our How we calculate page.
Rectangles and squares
Multiply the length by the width, both in metres: a room 4 m by 3.5 m is 4 × 3.5 = 14 m². If you measured in centimetres, divide each by 100 first (350 cm = 3.5 m).
L-shapes and odd shapes
Split the space into rectangles and add them together. Triangles are base × height ÷ 2, circles are π × the radius squared (3.14 × half the width × half the width), and a half circle is half of that. Take away anything you won’t cover, such as a kitchen island or a hearth.
Square feet and metres
1 m² is 10.764 ft², and 1 ft² is 0.093 m². If you measured in feet and inches, the calculator converts them for you (1 ft = 0.3048 m, 1 in = 2.54 cm) and shows the result both ways.
Examples
Square metres for common rooms and gardens
A few everyday areas, worked out with the calculator. Odd shapes are just rectangles, triangles and circles added or taken away.
Worked out with the calculator above. 1 m² = 10.764 ft²; 1 ft = 0.3048 m. Before buying flooring, tiles or turf, add extra for cuts.
Tips
Measuring and buying by the square metre
The calculation is simple; the care goes into measuring well and buying a little extra.
Measure well
Use a tape measure or laser measure and write each figure down. Measure at the widest point and measure both ends of the room, as walls are rarely perfectly straight. Include alcoves and bays as separate areas, and round up to the next centimetre.
Add extra for cuts
Flooring, tiles and turf come in fixed sizes, so some is cut away at the edges. Allow about 5% extra for a simple rectangular room, 10% for most rooms and 15% for diagonal or herringbone layouts, or rooms with lots of corners.
Use your result
Prices for flooring, carpet, turf and paving are usually per m², so enter the price in step 4 for a cost. For walls, the Paint Calculator, Wallpaper Calculator and Tile Calculator take off doors and windows for you.
Explore more tools
More practical tools, all in one place
Use simple checks, pickers and planners to make better decisions about your home, equipment and energy use.
Electricity Cost Calculator
Find out how much your appliances cost to run per day, month and year.
Replace or Keep
Compare the running cost of your current appliance with potential replacements.
Dehumidifier Picker
Find the right size and type of dehumidifier based on your room and usage.
Off-Grid Planner
Estimate your daily power needs and the battery, solar and inverter capacity to supply them.
Damp & Mould Check
Check whether a window or wall will get condensation or mould, and what humidity keeps it dry.
Plug-in Solar Payback
See what a plug-in (balcony) solar kit would save and how many years it takes to pay for itself.
Heating Cost Compare
Compare what it costs to heat a room with gas, oil, electric heaters, storage heaters or a heat pump.
Radiator & BTU Calculator
Work out what size radiator a room needs, in watts and BTU, for a boiler or a heat pump.
Paint Calculator
Work out how much paint a room or the outside of a house needs, and which tins to buy.
Concrete Calculator
Work out the concrete for a slab, footing, fence posts or steps, and the cement, ballast or bags to buy.
Tile Calculator
Work out how many tiles, boxes, adhesive and grout a floor or wall needs.
Wallpaper Calculator
Work out how many rolls of wallpaper a room or feature wall needs, allowing for the pattern repeat.
Gravel Calculator
Work out the tonnes and bags of gravel, chippings or sub-base for a path, border or driveway.
Decking Calculator
Work out the deck boards, joists and screws or clips for a timber or composite deck.
Flooring Calculator
Work out the packs of laminate, wood or click vinyl flooring a room needs, with underlay and beading.
Solar Panel Calculator
See what solar panels on your roof would make and save, and how many years they take to pay back.
Heat Loss Calculator
Estimate your whole home's heat loss, the heat pump size it needs and what heating costs a year.
Cable Size Calculator
Work out the cable size and fuse for a 12 V, 24 V or 48 V circuit in a van, boat or off-grid system.
EV Charging Cost
See what an electric car costs to charge per mile, per charge and per year, and the saving over petrol.
Laundry Symbols
Tap the symbols on a care label to see what they mean and the wash, dry and iron settings to use.
U-Value Calculator
Build up a wall, loft, roof or floor layer by layer to see its U-value and what its heat loss costs.
Curtain Size Calculator
Work out the pole length, curtain width and drop, the ready-made size to buy and the fabric to make them.
TV Size Calculator
Find the best TV size for where you sit, or the best seat for your TV, and how high to mount it.
Light Bulb Finder
Find the fitting, brightness and colour of the LED to replace any bulb, and keep a list of your bulbs.
Common questions
Frequently asked questions about square metres
Common questions about working out area, converting units and buying materials.
How do I work out square metres?
Multiply the length by the width, both in metres. A room 4 m long and 3.5 m wide is 4 × 3.5 = 14 m². For an odd-shaped space, split it into rectangles, triangles and circles, work out each one and add them together.
How many square feet are in a square metre?
One square metre is 10.764 square feet. To turn square feet into square metres, divide by 10.764 (or multiply by 0.0929): 150 ft² is about 13.9 m².
How do I measure an L-shaped room?
Split it into two rectangles, measure each one and add the two areas together. For example, 5 × 4 m plus 2 × 1.5 m is 20 + 3 = 23 m². In the calculator, add a second area for the second rectangle.
How do I work out the area of a circle in m²?
Measure across the middle (the diameter), halve it to get the radius, then multiply the radius by itself and by π (3.14). A round patio 3 m across has a radius of 1.5 m, so its area is 3.14 × 1.5 × 1.5 = 7.07 m².
How do I convert feet and inches to square metres?
Turn each measurement into metres first: feet × 0.3048 plus inches × 0.0254. A room 13 ft 1 in × 11 ft 6 in is 3.99 m × 3.51 m, which is 13.98 m². The calculator does this for you when you pick Feet and inches.
How much extra should I order for waste?
For flooring, tiles or turf, about 5% extra for a simple rectangular room, 10% for most rooms and 15% for diagonal or herringbone layouts, or rooms with many corners. Paint and wallpaper are worked out differently: use the Paint and Wallpaper Calculators.
What is the average size of a room in m²?
It varies a lot. In the UK, the national space standard for new homes asks for at least 11.5 m² for a double bedroom and 7.5 m² for a single bedroom. Living rooms are often 15 to 20 m². Measure your own room for an accurate figure.
Are the results exact?
The maths is exact, but the result is only as good as your measurements. Rooms are rarely perfectly square, so measure at the widest points, round up and check quantities with your supplier before you buy.