How to Measure a Room Before Buying Furniture

Measuring a room sounds like one number by another number. It is actually six, and the two that cause the most trouble are not about the room at all.

The six

1. Length and width of the clear floor. Not wall to wall. Wall to the nearest thing that is not moving: a radiator, a chimney breast, a skirting board, a kitchen unit.
2. Ceiling height, and the height under any beam, light fitting or sloping section.
3. Every door arc. Mark it on the floor. A door opening into the room removes roughly a quarter circle of 800 mm radius from the usable area.
4. Window sills, radiators and sockets, with their heights. A sofa back across a socket is a decade of annoyance.
5. The walking routes you actually use. Door to sofa, door to window, kitchen to table. Walk them and measure the narrowest point.
6. The route in from the street. Front door, hallway, stairs, turns, lift. This is the one that cancels orders.

Walls are not straight

Measure every dimension at both ends and in the middle. Older buildings routinely vary by 20 to 30 mm across a room, and new ones are not always better. Use the smallest number you get.

The same applies to ceiling height if you plan to tilt something tall on its end during delivery.

The clearances to design around

Situation	Space needed
Walking past furniture, one person	600 mm
Walking past, two people	900 mm
Squeeze route used daily	450 mm minimum
Pulling a dining chair out	750 mm behind the table edge
Walking behind a seated person	900 to 1000 mm
Opening a cabinet door	Door width plus 300 mm to stand
Behind a floating sofa	300 mm, or 600 mm if used as a route

The dining case is set out fully in dining table clearance.

Tape on the floor

Numbers do not tell you how a room feels. Masking tape does.

1. Mark the footprint of each piece you are considering.
2. Mark the door arcs.
3. Put a chair or a stack of boxes where the tall pieces will go, so you can see heights.
4. Live with it for a day. Walk it in the dark.

You will find out whether the route works, whether the door still opens, and whether the room still feels like a room. The Round Table is 1000 mm across and wants about 900 mm around it, which is 2800 mm of clear floor each way. On paper that is a number. On the floor in tape it is obvious.

The route in

Measure, in this order, from the street:

• Entrance door width, with the door removed where possible, which is usually 40 mm more.
• Hallway width, and the width at any turn.
• Stair width, and the ceiling height above the turn, which decides whether something can be tilted.
• Lift car dimensions including the door and the internal diagonal.
• The last door into the room.

Then compare with the smallest cross-section of the piece, not its largest. Many pieces go through a tight door on their end or their side. The full method is in will it fit through the door.

Write it down in one place

A photo of a tape measure is not a record. Sketch the room, mark every number on the sketch, including heights and the route, and keep it on your phone. You will use it for years and for every future purchase.

Two habits that save money

• Measure the thing you already own that works. If your current table is comfortable at a certain size, that number is more useful than any guideline.
• Buy for the normal week, not for the largest gathering of the year. A table that seats six every day and eight once a year is a better table than one that seats eight every day badly.

Measure what you already own

The most useful numbers in this exercise are not guidelines, they are the dimensions of the furniture you already live with and have opinions about.

• The table you find comfortable: length, width, height, and the gap under it.
• The chair everyone fights over: seat height, seat depth, arm height.
• The sofa that is too deep: seat depth compressed, with someone on it.
• The shelf that is too shallow: internal depth.

Take ten minutes and write these down once. They turn every future purchase from a guess into a comparison, and they are personal to your household in a way that no published standard is.

Photograph the room with a reference

Stand a metre stick or a broom against the wall and photograph each wall of the room. A photo with a known length in it lets you check proportions later, and it reminds you of the socket, the radiator and the awkward corner that you will otherwise forget by the time you are looking at furniture.

Keep those photos with the sketch. Between them they answer almost every question a seller will ask you.

Reality check

• Clear floor, not room dimensions.
• Door arcs take more floor than anything else you forget.
• Measure walls at both ends. They are not parallel.
• The route in is a separate exercise from the layout.
• Tape on the floor for one day answers questions no plan can.