Measure your room yourself: the 8 dimensions that change a quote
Before the first quote: the 8 dimensions to take at home, the 3 classic mistakes, and how to send them to your contractor.
The contractor asks "do you have measurements?" You send three WhatsApp photos and "the room is about 13 feet." Two weeks later the quote talks about 120 sq ft when you count 140: or the other way round. Nobody cheated: nobody measured the same thing.
A 16-foot tape and twenty minutes are enough to change the quality of quotes. You don't need to be a surveyor. You need to know what to measure, and especially how: because three classic mistakes throw off almost every DIY survey.
Amounts cited below are indicative ballparks, not binding quotes. Download the PDF sheet to tick the 8 dimensions room by room.
Why 8 inches change a quote
A contractor prices areas and linear metres. Eight inches too many (or too few) on a 13-foot wall means:
- an extra roll of wallpaper or tin of paint;
- a floor layout that no longer lands;
- a made-to-measure cabinet ¾ inch too wide, and therefore remade.
On a 130 sq ft kitchen, a ceiling height read as 8'2" instead of 8'10" is often an 8-10% gap on paint and wall tile. Invisible in a photo.
The goal is not millimetre precision. It is to arrive with written dimensions, taken the same way, that each contractor can check in five minutes instead of rebuilding from scratch.
The 8 dimensions to take
Grab a notebook (or the printable sheet). For each room in the project:
- Length × width, wall to wall. Put the tape on the floor, against the wall, not above the skirting. Skirting eats ½-¾ inch on each side: on a wardrobe, that is enough to jam a cabinet.
- Ceiling height. Measure at least two points: a corner and the middle of the room. More than ¾ inch difference: write it down (old floors or an uneven dropped ceiling).
- Both diagonals. If they differ by more than an inch, the room is not rectangular. The contractor needs that before laying a floor or ordering a worktop.
- Each door: clear opening width (the leaf open, not the outer frame) and swing direction. A fridge or oven that hits a door is a £300-600 relocation quote you could have avoided.
- Each window: width, and sill height (finished floor to the underside of the window). That dimension decides whether a worktop or radiator fits underneath.
- Projections: radiator, chimney breast, duct, niche, consumer unit. Note width × depth from the nearest wall.
- Service axes. From a reference corner (mark it with a pencil cross), measure the axis of the sink, WC, water supplies, and sockets you want to keep. Moving a waste pipe 6 feet is often £300-600.
- Site access. Floor, lift (cabin size if you have it), parking, building rules (hours, protecting common areas). A 4th floor with no lift is often 10-15% extra labour on heavy items.
The 3 mistakes that throw off almost every home survey
- Measuring skirting to skirting, or above the skirting, instead of wall to wall on the floor. Furniture and floors sit on the wall face.
- A single ceiling height, taken "by feel" in the middle of the room. Corners tell a different story, especially in older buildings.
- Skipping the diagonals. A "rectangle" of 12'6" × 13'9" with 3 inches of diagonal gap will not take 24" tiles without ugly cuts: nor a standard corner unit.
A set of full-wall photos (not tap close-ups) completes the notebook: 4 walls, ceiling, floor, each opening, meters. Photos do not replace dimensions; they make them checkable.
| You send… | What the contractor can price |
|---|---|
| Photos only | A wide range, lots of assumptions |
| Verbal sizes ("about 13 feet") | A quote, then change orders later |
| Written sizes + photos + diagonals | A comparable quote, verifiable on the visit |
How Kodarch can help
Putting the 8 dimensions on a 2D plan beats a lost notebook and "I wrote it on another scrap." You see immediately whether the room closes, you test a piece of furniture, and you send the same link to three contractors: same dimensions, fewer back-and-forths. The simulator then gives an indicative range: not a quote. For the rest of the brief (questions, photos, access), see Preparing your project. On the contractor side, the mirror guide Site survey: 8 measurements covers what they will check at yours. To get started: Kodarch for homeowners.
Common mistakes to avoid
- Sending dimensions in a voice note: they will never be copied the same way twice.
- Measuring walls above furniture still in place (you are measuring the gap, not the room).
- Forgetting the unit. "380" without a unit is 3.80 m or 15 inches?
- Mixing up door clear opening and overall frame width.
- Surveying after asking for quotes: each contractor will already have invented their own sizes.
Frequently asked questions
Do I need a laser measure? Not for a first brief. A 16-foot tape and someone to hold the end is enough. Lasers help beyond ~20 feet or on high ceilings.
Centimetres or millimetres? Centimetres (or the nearest ½ inch). Millimetres feel precise; they do not change a painting quote. For made-to-measure joinery, the contractor will remeasure to the millimetre.
The room is not rectangular: what then? Note all 4 walls and both diagonals. A dimensioned sketch (even ugly) beats a rectangle "to keep it simple."
Do I need to measure the whole home? No: only the rooms in the project, plus circulation (hallway, landing) if materials have to pass through.
In short
Quotes diverge because nobody measured the same room. Eight written dimensions (wall to wall, height, diagonals, openings, projections, services, access) are enough to frame the first price. Then a shared plan stops you typing them three times.