Blog · Measuring
How to measure a room for flooring, paint and furniture
Measure the length and width of the floor at its widest points and multiply them to get the floor area. For an L-shaped room, split it into rectangles and add them up. For paint, measure each wall's width times the ceiling height, then subtract doors and windows. Order 5 to 10% more flooring than the area to cover cuts, about 20% more for tile, and 15 to 20% more for diagonal or herringbone layouts.
What you need
- A tape measure (a 5 m or 25 ft one is enough for most rooms) or a laser distance meter.
- Paper and a pencil to sketch the room, or a floor plan app.
- A second person helps with long walls, but a laser meter works fine alone.
Measure the floor area
- Sketch the room's outline, including alcoves, bay windows and chimney breasts.
- Measure the length of the room along one wall, at floor level, from wall to wall. Skirting boards and baseboards don't count.
- Measure the width the same way.
- Multiply length by width. A room 4.2 m long and 3.5 m wide has a floor area of 14.7 m². In feet, 14 ft by 11 ft 6 in is 14 x 11.5 = 161 sq ft.
- Measure each wall twice, once near each end. Old walls are rarely square, and if the two numbers differ, use the larger one for ordering material.
L-shaped and irregular rooms
Split the floor into rectangles that don't overlap, measure each one, and add the areas together. A room that is 5 x 4 m with a 2 x 1.5 m alcove has 20 + 3 = 23 m². For a bay window or a curved wall, measure the rectangle that encloses it and treat the extra as part of your waste allowance.
Measure walls for paint or wallpaper
- Measure the width of each wall and the ceiling height.
- Multiply width by height for each wall and add the walls together.
- Subtract doors and windows. A typical interior door is about 2 m² (21 sq ft) and a typical window about 1.4 m² (15 sq ft), but measure yours if they are larger.
- Multiply by the number of coats (usually two), then divide by the coverage on the tin. Most wall paint covers roughly 10 m² per litre (350 to 400 sq ft per gallon) on smooth, primed walls.
Wallpaper is sold by the roll, not by area. Divide the room's perimeter by the roll width to get the number of drops, then work out how many drops each roll gives at your ceiling height, allowing for the pattern repeat.
How much extra to order
Flooring always loses some material to cuts at the walls and around door frames. Common allowances:
| Layout | Extra to order |
|---|---|
| Hardwood or laminate, straight lay | 5 to 10% |
| Tile | About 20% |
| Diagonal, herringbone or other patterns | 15 to 20% |
Round up to whole boxes, and keep a box or two of the leftovers. Flooring batches vary in colour, and a matching board is hard to find years later when one gets damaged.
Measure with your iPhone instead
On an iPhone or iPad with a LiDAR sensor (Pro models since 2020), a room scan measures every wall, door and window in about a minute and gives you the floor area and wall lengths automatically. On other iPhones, you can film a short walkthrough and let AI draw the plan, or type in your tape measurements and get a scaled floor plan. CamPlan does all three, and our guide on whether you need LiDAR explains the difference.
For ordering material, check one or two key walls with a tape measure even after a scan. If they agree to within a centimetre or so, the plan's scale is right. See how accurate iPhone room scans are.
FAQ
How do I calculate the square footage of a room?
Multiply the length by the width in feet. A 12 ft by 10 ft room is 120 sq ft. For an L-shaped room, split it into rectangles, calculate each one, and add them together.
Should I measure from the skirting board or the wall?
For flooring, measure wall to wall at floor level and ignore the skirting board, because the flooring runs underneath it or up to it with an expansion gap. For furniture, measure between the skirting boards, since that's the space the furniture actually has.
How do I convert square feet to square metres?
Divide square feet by 10.764. 161 sq ft is about 15 m². To go the other way, multiply square metres by 10.764.
How much extra flooring should I buy?
5 to 10% for hardwood or laminate laid straight, about 20% for tile, and 15 to 20% for diagonal or herringbone layouts. Check the manufacturer's recommendation too.
Try CamPlan
Scan with LiDAR, film a short video or draw by hand, and get an editable 2D and 3D floor plan. Free to start on iPhone, iPad and Mac.
Download on the App StoreRelated posts
- Do you need LiDAR to scan a room?
Which iPhones and iPads have LiDAR, what a LiDAR room scan gives you, and how to make a floor plan on an iPhone without it.
- How accurate are iPhone room scans?
What the research says about iPhone LiDAR and RoomPlan accuracy, where scans go wrong, and how to check a scanned floor plan before you order materials.