How to measure a room for a floor plan
Ten minutes with a tape measure gives you a plan you can trust. Here is the order that avoids the usual mistakes.
What you need
- A tape measure of 5 m or longer, or a laser distance meter (faster for long rooms, and easier on your own).
- Paper and a pencil for a rough sketch. It does not need to be neat; it is a place to write numbers.
- A second person helps with long walls but is not essential.
1. Sketch the room first
Draw the outline of the room by eye, with every wall, the doors, the windows and anything fixed: a chimney breast, a radiator, a built-in cupboard. Number the walls clockwise from the door. You will write each measurement on the sketch next to the wall it belongs to, so nothing gets mixed up later.
2. Measure each wall at floor level
Measure from one wall face to the opposite wall face, just above the skirting board, keeping the tape straight and level. Floor plans use these inside sizes, which is also what PlanPencil asks for. Write the size in centimetres (or feet and inches) on the sketch.
Measure each wall twice, at both ends of the room if you can. Old walls are often not parallel; if the two numbers differ by more than about 2 cm, write both and use the smaller one for furniture.
3. Check whether the room is square
Measure both diagonals, corner to corner. In a true rectangle they are equal. If they differ by a few centimetres the room is slightly out of square; that is normal and does not matter for planning furniture, but it matters for fitted kitchens and wardrobes.
4. Doors and windows
For each door and window, measure from the nearest corner to the edge of the opening, then the width of the opening itself (the frame-to-frame gap). Note which way each door opens and on which side the hinges are: a door swing takes floor space that furniture cannot use. For windows, also note the height of the sill from the floor if you want furniture under it.
5. Fixed things and heights
Measure the position and size of radiators, sockets you want to keep free, pipes and anything built in. Measure the ceiling height in one or two places, and note sloping ceilings or beams. These do not change the floor area, but they decide where tall furniture can go.
6. Put it into a plan
Open the floor plan maker and add the room by its inside width and length. Add doors and windows on the right walls with the sizes you measured, then the furniture. PlanPencil shows the area and the gaps around each piece, and the PDF prints to scale so you can check any size with a ruler. If you have only the sizes and no sketch, the floor plan generator turns a list of room sizes into a plan.
Common mistakes
- Measuring over the skirting board top instead of at floor level: skirting can take 1–2 cm off each side.
- Reading the tape from the wrong end of the hook, or bending it around a corner.
- Forgetting door swings, radiators and sockets, then finding the furniture blocks them.
- Rounding every size up; round down for anything that has to fit.