Room Area Calculator

Calculate the area of a rectangle or an L-shaped room

This room area calculator uses the dimensions you enter. For a rectangle, it multiplies width by depth. For a simple L shape, it subtracts one rectangular cutout from the surrounding rectangle. The result is displayed in your chosen square units and converted to the other unit system.

Use metres or feet consistently. A width in metres and a depth in feet do not belong in the same calculation unless one has first been converted.

Measure the boundary you intend to count

Decide whether you need floor area between internal wall faces, a larger envelope, or another clearly defined boundary. Measure both overall dimensions using that convention. Do not include an exterior wall thickness in one direction and exclude it in the other without understanding what the result represents.

For an irregular room, sketch the outline before entering numbers. Mark recesses, projections, and built-in objects. The calculator handles one rectangular subtraction; more complex shapes should be split into several non-overlapping rectangles and their areas combined separately.

Rectangular room example

A room measuring 5 m by 4 m has an area of 5 × 4 = 20 m². Leave both cutout inputs at zero for this case. The calculator also shows approximately 215.28 ft².

The displayed result is only as reliable as the measurements. If a wall is not straight or two opposite sides have different lengths, a single rectangle may be a rough approximation. Measure the actual shape when the distinction affects a decision.

L-shaped room example

Imagine a 6 m by 5 m surrounding rectangle with a missing corner measuring 2 m by 1.5 m. The full rectangle is 30 m² and the missing corner is 3 m². The remaining floor area is 27 m².

Enter 6 and 5 as the overall dimensions, then 2 and 1.5 for the cutout. The cutout must fit within the overall rectangle. A cutout larger than the room dimension is rejected rather than producing a misleading result.

This subtraction describes a simple shape; the drawing's orientation does not change the arithmetic. Make sure you subtract the absent area rather than a room section that is actually included in your measurements.

Square metres and square feet

A foot is exactly 0.3048 m, so a square foot is 0.09290304 m². Area conversion squares the length relationship. Multiplying square metres by a length-only conversion factor gives the wrong answer.

The tool applies the area conversion for you. Its rounded display is useful for comparison, while your project may need a different reporting precision. Avoid describing a roughly measured room to several decimal places as though it were a survey.

Area is not a purchase quantity

A net floor area does not automatically tell you how much flooring, carpet, or tile to order. Product dimensions, cutting patterns, offcuts, joins, packaging, and the shape of the room can change the required quantity. Follow the product guidance and the installer’s measurement process for purchasing decisions.

Likewise, this calculator does not determine official property area under a local measurement standard. Such standards may define wall boundaries, shared areas, low headroom, and exclusions differently. Use the applicable method if you need a formal property figure.

Make the number useful in a layout

Use the result to understand the size of the space, then compare actual furniture footprints and routes in the room layout planner. Two rooms with equal area can have very different proportions and usability. A narrow 2 m by 10 m space is not interchangeable with a 4 m by 5 m room merely because both total 20 m².

Frequently asked questions

Does this handle a circular room?

No. The available calculation is rectangular area with an optional rectangular cutout. Use the appropriate geometry for curved or triangular sections and keep the components separate.

What if my room has two recesses?

Divide it into non-overlapping rectangles or calculate each missing rectangle separately. Do not enter one oversized cutout that removes floor area between the recesses.

Can I calculate wall paint area here?

This tool calculates a horizontal floor area. Wall area requires wall length multiplied by height, with appropriate openings and other adjustments. Those are different inputs.

What should I save with the result?

Keep a sketch, the units, the measured dimensions, and the boundary convention you used. Read how to calculate room area for a step-by-step checking workflow.