Ergonomic Desk Dimensions for Built-In Home Offices in Spare Bedrooms

Standard desk height for a seated user is 720–740mm from floor level for an average adult — but this assumes the user's feet rest flat on the floor in a good chair. For taller users (above 1.85m), a desk height of 750–780mm is more appropriate. Desk depth should be a minimum of 600mm to allow a monitor at the correct 500–600mm viewing distance with space in front for a keyboard and a palm rest. A depth of 700mm is noticeably more comfortable for extended working sessions. Width should accommodate monitor, keyboard, and a writing or secondary device space — a minimum of 1200mm, ideally 1400–1600mm.

The clear height under the desk surface to the floor should be a minimum of 650mm — this accommodates most seating heights and allows freedom of leg movement. Under-desk drawer pedestals on the left or right should not encroach on this clearance zone. A compact two-drawer pedestal of 450mm width is the largest under-desk element compatible with comfortable seated knee clearance in most configurations.

The published standards are averages, and averages are only a starting point. Before I draw a fitted desk I want to know who will sit at it, for how many hours a day, and what they do there. The quickest check is seated elbow height: sit in your work chair with feet flat and shoulders relaxed, and measure from the floor to the underside of your forearm with the elbow at roughly ninety degrees. The worktop wants to be at, or a touch below, that height. For most adults that lands in the 720–740mm band, but I have built desks at 700mm for one client and 770mm for another, and both were right.

The chair matters as much as the desk. If you already own a decent task chair, I measure the desk around it — seat height range, armrest height, base diameter. If you are buying one, buy it before the survey. A fitted desk designed around a dining chair and then used with a high-backed office chair with fixed arms is a common and avoidable mismatch.

Your eyes should sit roughly level with the top of the screen, at a viewing distance of about arm's length — 500–600mm for a 24 to 27 inch monitor. Work backwards from that and the case for a 600–700mm deep worktop makes itself: the monitor base needs 200mm or so, the screen needs to sit far enough away from your face, and there must still be room for a keyboard and a strip of clear worktop in front of it for your wrists. On a 450mm-deep top the screen ends up too close and the keyboard hangs off the front edge.

In alcove builds there is a second constraint people miss: the first shelf above the desk. If shelving continues up the alcove, I keep at least 500mm clear between worktop and the underside of the first shelf so a monitor fits beneath it with adjustment room. A monitor arm bolted through the worktop frees up the desk surface and lets the screen float at exactly the right height — worth specifying before fabrication so I can reinforce the fixing point.

Leave 80–100mm of clear worktop between the front edge and the keyboard for the heels of your hands. It sounds trivial; it is the difference between comfortable typing and aching wrists by Thursday. I am generally against pull-out keyboard trays in fitted desks — they steal knee clearance, rattle, and put the keyboard on a different plane from the mouse. A worktop at the correct height makes the tray unnecessary.

The front edge itself deserves thought. A crisp square edge looks sharp in photographs and digs into forearms in use. I ease desk edges with a small round-over or a pencil arris — enough to be kind to skin without reading as a bullnose. On oak tops a slightly larger chamfer works well and takes the inevitable knocks better than a sharp corner.

A desk is only usable if you can get in and out of it. I allow a minimum of 1000mm clear from the front edge of the worktop to the nearest obstruction — bed, wall, wardrobe door — so the chair can push back and you can stand without a three-point turn. In spare bedrooms this measurement, not the alcove width, is usually what decides where the desk goes.

Watch door swings too. A desk chair parked in the arc of the room door gets clipped every time someone comes in, and in a small room that is constantly. Where space is genuinely tight I will sometimes orient the desk across the alcove face rather than inside it, or specify a chair with a smaller base, but I would rather lose 50mm of worktop depth than lose the ability to sit down properly.

A fixed built-in cannot do what an electric sit-stand frame does, and it is better to be honest about that than to pretend otherwise. What a built-in can do well is a dedicated standing-height section — a raised return or counter at roughly standing elbow height, which for most adults falls between 1000mm and 1100mm. That suits a laptop perch for calls, a printer counter, or a place to stand and read drawings or paperwork.

Where a client genuinely alternates between sitting and standing all day, the best fitted answer is usually to design the cabinetry around a bay that takes a freestanding electric desk — shelving and storage built to frame it, with cable routing planned so the desk can rise and fall without dragging leads. It looks integrated, and the moving part remains a replaceable piece of furniture rather than joinery.

Light position matters more than light quantity. A window directly behind the monitor silhouettes the screen; a window directly behind you reflects in it. Side-on to the window is the comfortable arrangement, and in an alcove desk that usually decides which alcove the desk goes in. It is worth settling this before the joinery is designed, not after.

For task lighting I fit a warm-white LED strip under the first shelf above the desk, set behind a small pelmet or in a routed channel with a diffuser so you see the light on the worktop, not the strip itself. Positioned towards the front of the shelf, it lights your keyboard and papers without bouncing off the screen. Put the switch or dimmer at the desk, not by the door — a small detail that decides whether the light actually gets used.

Two people working side by side need 1200mm of width each as a working minimum — enough for a monitor, keyboard and elbows without clashing. A 2400mm run across a full wall does this comfortably; squeezing two people into 1800mm works only if they are rarely there at the same time. Give each position its own cable grommet and its own drawer, because a single shared pedestal in the middle serves nobody.

For mixed adult and child use, build at adult height and let chairs do the adjusting. A height-adjustable chair with a footrest puts a nine-year-old at the right relationship to a 730mm worktop, and the desk is still right for them at nineteen. The reverse — a low desk for a small child — is obsolete within a couple of years and cannot be raised without rebuilding.

Most of my fitted desks get a sprayed MR MDF top, built up to 25–30mm finished thickness, in a durable lacquer that shrugs off coffee cups and laptop feet. It matches the painted cabinetry around it and can be refinished years down the line. The step up is oak — either an oak-veneered birch ply top with solid oak lippings, which stays flat and gives clean grain across the width, or full solid oak, which marks more readily but ages into character rather than just wearing.

Sag is the failure to design out. A desk top is a shelf you lean on, and spans over about 1000mm need support beyond the two side battens — a continuous rear batten always, plus a mid-span gallows bracket, a pedestal, or a vertical division on longer runs. Getting the support strategy right at design stage costs nothing; a dip in the middle of a desk two years in is not fixable without taking the top off.

The sequence on a typical alcove desk: survey and user measurements first, then socket positions agreed and any electrical work done before I install — an electrician can add a double socket and data point at desk height far more neatly before cabinetry covers the wall. In the workshop I build the carcasses and cut the top oversize; on site the top is scribed to the alcove walls, which in Berkshire's Victorian and 1930s stock are reliably out of square, then fixed to levelled battens. Cabinetry, shelving and lighting follow, decoration last.

The mistakes I get asked to put right are consistent. Desks built too high because a worktop was dropped onto a standard 720mm kitchen carcass without checking the finished height. Shelves pitched too low over the monitor. Depth traded down to 450mm to keep the room feeling big, leaving a desk nobody can work at for a full day. Ten minutes with a tape measure and an honest conversation about how the desk will be used prevents all three.