How to work out a room's area from a floor plan

Room area is length times width for a simple rectangle. Real rooms have bays, chimney breasts and L-shapes. Here's how to get an accurate figure from a plan without doing the sums by hand.

Rectangular rooms

1. Set the scale

   Add the plan to the board and Calibrate on a dimension you know.

2. Draw over the room

   Pick the rectangle tool (R) and drag from one inside corner of the room to the opposite one.

3. Read the area

   Select the rectangle. The bar at the bottom shows its size, area and perimeter. You can type an exact width or height there too.

L-shaped and irregular rooms

Use Lasso fill (G): draw round the inside of the walls, going corner to corner, and let go near where you started. Select the fill to see its area and perimeter. You can also draw a straight-sided outline with the line tool (L), clicking each corner and finishing on the first one.

Alternatively, split the room into rectangles and add their areas together. That's often the most accurate way for rooms with long straight walls.

Converting between square metres and square feet

1 m² is about 10.76 ft², and 1 ft² is about 0.093 m². Calibrate in the unit you want the answer in and ScaleDraw does the conversion for you.

Which area do you need?

• Flooring and carpet: the floor inside the walls, plus an allowance for cutting. See how much flooring do I need.
• Estate agents and valuations usually quote gross internal area: inside the outer walls, including internal walls.