Square Metres Calculator UK

Whether you are buying carpet, planning a loft conversion, working out how much paint you need, or simply trying to understand the size of a property listing, knowing how to work out square metres is an essential everyday skill. This guide explains everything clearly — from the basic formula to measuring L-shaped rooms, converting metres to sq metres, and understanding exactly how big a square metre really is.

What Is a Square Metre?

A square metre (m²) is a unit of area — it measures the two-dimensional space inside a shape. One square metre is the area of a square with sides measuring exactly 1 metre. To picture it: a large bath mat, a small coffee table top, or roughly two A0 poster sheets laid side by side is approximately 1 m².

How to Work Out Square Metres of a Room (Step by Step)

For a rectangular room — which covers most bedrooms, living rooms and kitchens — the process is straightforward:

1. Get a tape measure — a retractable steel tape or a laser measuring tool both work well.
2. Measure the length of the room in metres, from wall to wall at the longest point. Note it down.
3. Measure the width of the room in metres, from wall to wall at the widest point perpendicular to the length.
4. Multiply length × width. The result is the area in square metres.
5. For flooring or tiling, always add 10% to the total to account for cuts and waste.

Converting Metres to Square Metres — Why You Need Two Measurements

One of the most common searches is "convert metres to sq metres" — but it is important to understand that this is not a simple one-step conversion like converting kilometres to miles. You cannot convert a single metre value into square metres because they measure different things:

• Metres measure a line (one-dimensional)
• Square metres measure a flat area (two-dimensional)

To get square metres, you need to multiply two metre measurements together. The formula is always: Area (m²) = Length (m) × Width (m).

Area Formulas for All Room Shapes

How to Work Out the Square Metres of an L-Shaped Room

L-shaped rooms are very common in UK homes — open-plan kitchen-diners and knocked-through reception rooms often form an L shape. The approach is to mentally divide the room into two rectangles, calculate each area separately, then add the two figures together.

Tip: When dividing an L-shape, it does not matter how you split it — you will always get the same total area as long as you do not count any part twice or miss any part.

UK Room Size Reference Table

Not sure if your calculated area sounds right? Use this table as a guide to typical UK room sizes:

Metres to Square Metres: Common Examples

These examples show how different length measurements combine to give a square metre area:

Square Metres Conversion Table

Practical Uses: Why Square Metres Matter in the UK

Flooring and carpets: All UK flooring retailers sell by the square metre. Carpet, laminate, LVT, and ceramic tiles are all priced per m². Calculate your floor area carefully, then add 10% for waste, cuts, and alignment.

Wall paint: A standard 2.5-litre tin covers approximately 25–30 m² in one coat. For a room with a total wall area of 40 m² (minus windows and doors), you would typically need two tins for two coats.

Property listings: UK estate agents increasingly list floor area in square metres alongside square footage. The Royal Institution of Chartered Surveyors (RICS) recommends square metres. The average UK terraced house is approximately 85 m², a semi-detached around 95 m², and a detached house around 130 m².

Garden and landscaping: Turf, gravel, decking boards and artificial grass are all priced by the square metre in the UK. For garden paving slabs, typical coverage is 1 m² per slab for large-format slabs, so your calculated area equals the number of slabs needed.

Loft conversions and extensions: Building regulations require minimum floor areas for habitable rooms. For example, a bedroom must generally be at least 6.5 m² in floor area to be considered a proper bedroom for property listing purposes.

UK Property Sizes in Square Metres

The Nationally Described Space Standard (NDSS), introduced by the UK government in 2015, sets minimum floor area requirements for new dwellings. Here is how common property types compare:

• 1-bedroom, 1-person flat (new build minimum): 37 m²
• 1-bedroom, 2-person flat (new build minimum): 50 m²
• 2-bedroom, 4-person house (new build minimum): 79 m²
• 3-bedroom, 5-person house (new build minimum): 93 m²
• Average UK new-build home (2025): approximately 76 m²
• Average UK existing home: approximately 92 m²

How do I work out the square metres of my room?

Measure the length of the room and the width of the room, both in metres. Then multiply the two numbers together. For example, a room 4 metres by 3.5 metres is 4 × 3.5 = 14 m². Use the calculator above for instant results including conversions to square feet.

How do I convert metres to square metres?

You cannot convert a single metre measurement to square metres — you always need two measurements (length and width). Multiply them together: Area (m²) = Length (m) × Width (m). This is because metres measure length (one dimension) while square metres measure area (two dimensions).

What is 5 metres by 4 metres in square metres?

5 metres by 4 metres equals 20 square metres (5 × 4 = 20 m²). This is approximately the size of a standard double bedroom in the UK and equals about 215 square feet.

How big is a square metre in real life?

One square metre (1 m²) is the area of a square with 1-metre sides. To visualise it: it is roughly the size of a large bath mat, a small coffee table, or two A0 posters side by side. In square feet, 1 m² = 10.76 ft². A standard UK double bed is approximately 2 m², and a parking space is roughly 12.5 m².

How do I calculate the square metres of an L-shaped room?

Divide the L-shaped room into two rectangles. Measure and calculate each rectangle's area (length × width), then add them together. For example: Section 1 is 5 m × 3 m = 15 m²; Section 2 is 2 m × 3 m = 6 m². Total = 21 m². Our L-shaped room tab above handles this automatically.

What is the difference between square metres and metres squared?

In formal use, "square metres" and "m²" (metres squared) mean the same thing — a unit of area. However, in casual speech, "3 metres squared" can be ambiguous: it could mean 3 m² (an area of 3 square metres) or 3² = 9 m² (a square with 3-metre sides). To avoid confusion, always use "m²" or "square metres" in written form.

How many square metres is an average UK double bedroom?

A standard UK double bedroom is typically 10–15 m², with an average around 11–12 m². The minimum size to be legally marketed as a double bedroom is generally considered to be around 7.5 m² (though this is not formally defined in law). A generous master bedroom might be 16–20 m².

How do I measure an irregularly shaped room?

For irregular rooms, divide the space into simple shapes — rectangles, triangles, or semicircles. Measure each section separately, calculate each area using the appropriate formula, and add all the areas together. For very complex shapes, use the grid method: lay a 1 m² grid over a scale drawing and count the squares, estimating partial squares at the edges.