How to Measure Square Footage of a Room

Measure a room in three steps

Have a tape measure, a pencil and somewhere to record your measurements. A rough sketch is enough.

1. Sketch the floor.Mark the corners, alcoves and any parts you plan to leave out.
2. Measure and label each edge.For a rectangle, record length A and width B. Mark extra sections separately.
3. Calculate and check the total.Add the parts you need and subtract the parts you are leaving out. Count every part once.

This guide measures a floor or flat room footprint for a project. To measure a wall’s width and height, use the wall area calculator.

Measure a rectangular or square room

Record the units with the numbers

In the calculator’s ft + in mode, put feet in the ft box and inches in the in box. For 12 ft 6 in, enter 12 and 6. For inches only, leave ft blank.

Prefer decimal feet? Select Feet (ft) and enter 12.5. In ft + in mode, use decimal feet only with in blank or 0. For metric measurements, choose m, cm or mm; the result is shown in m².

For hand calculations, use the same length unit for both dimensions. 12 ft 6 in is 12.5 ft, so 12.5 ft × 10 ft = 125 sq ft.

Measure an L-shaped room

Picture a full rectangle around the L. Measure its full length A and full width B, then the two edges C and D of the missing corner. Use the inside wall edges for C and D, as shown.

Choose L-shaped room in the calculator. It already removes C × D. Do not add another subtracted section for that same missing corner.

You can also split the L into two non-overlapping rectangles and add them. Both methods should give the same area when they describe the same floor.

Add or subtract sections for other layouts

Draw lines on your sketch to divide the floor into simple shapes. Mark the dimensions for each part. Added parts must not overlap the main area or one another.

For a triangular part, measure its base and the height at a right angle to that base. Its area is base × height ÷ 2. The sloping side is not the height.

A shape’s dimensions do not tell the calculator where it sits. Check your sketch for overlaps. For curved or uneven boundaries, a simple-shape calculation may be an approximation.

Which parts of the room should you include?

First decide what you are measuring: the whole room footprint, or only the floor that will receive a particular material.

Closets and alcoves

Include them when they are part of your measurement or flooring project. If they already lie inside the main rectangle, do not add them again.

Movable furniture

A sofa or table does not change the room’s footprint. Do not automatically deduct it from the floor area.

Fixed cabinets, islands and columns

For a whole-room footprint, their presence does not shrink the room. For material coverage, check whether the product will be installed underneath or around them, then measure that chosen coverage.

Doorways between rooms

Decide which room includes the connecting floor strip and mark it on your sketch. Include it once.

Installation rules depend on the flooring. For example, floating flooring may need to remain free around fixed cabinets. Check your product’s installation instructions before deciding which surfaces to cover.

Measure several rooms separately

Name each room or floor area and record its own dimensions. Use Add another room or area in the area calculator for a separate space; use Add section for a part that changes one room’s result.

For example, the 125 sq ft room above plus an 8 ft × 10 ft room gives 125 + 80 = 205 sq ft. Check that connecting areas are not included in both rooms.

Adding room areas gives the total of the surfaces you measured. It does not determine a home’s official listing or appraisal area.

Before you use the result

• Every measured edge has a number and a unit.
• The sketch, chosen shape and input labels describe the same area.
• Extra sections do not overlap; missing corners are removed only once.
• Each room and section has complete, valid measurements.
• Measurements describe the actual space. Waste is added separately when estimating materials.

If you are ordering flooring, open the flooring calculator to enter a waste allowance, the product’s box coverage and its price. Measured area and purchased coverage are different quantities.