How to measure a small workspace before you buy anything

Number 1: how much depth the room can give up

Start with the room, not the desk. Measure from the wall you want the desk against to the nearest thing you cannot move — a bed, a sofa, a radiator, the swing of a door. Write that number down. It is the total budget, and everything else comes out of it.

Out of that budget the chair takes about 30 inches: roughly 20 for the chair itself and 10 more to push it back and stand up. A walkway past the back of the chair wants another 24 to 30 inches if anyone actually walks there.

So a 15⅜-inch desk in a room with 80 inches of wall-to-bed distance leaves about 35 inches of clear floor after the chair. A 24-inch desk in the same room leaves about 26. That nine-inch difference is why depth, not width, is the first thing to measure. Desk depths in our compact desk guide run from 15⅜ to 24 inches, and every one of them publishes the figure.

Number 2: the depth your monitor needs

This is the number that surprises people, and the reason a shallow desk is not automatically the right answer.

Canada's CCOHS describes the eye's resting point of accommodation as typically around 80 cm — about 31.5 inches — and its resting point of vergence further out still, averaging around 112 cm, or about 90 cm at a 30-degree downward viewing angle. It suggests an arm's length as a practical estimate of where a monitor should sit. UCLA's ergonomics guidance says the same thing more bluntly: sit at least an arm's length from the screen, then adjust for your own vision.

Now measure your monitor's stand. A typical 24 or 27-inch panel sits 8 to 10 inches forward of the back edge of its own base. On a 19⅝-inch-deep desk pushed against a wall, that puts the panel around 10 inches from the back of the desk, and your eyes are about 20 inches from it once you are sitting at the keyboard. That is a long way inside the distance CCOHS describes as comfortable.

There are two honest fixes and they cost different amounts:

• Buy the depth in the desk. Around 24 inches lets a factory stand put the screen at roughly arm's length. That is the deepest desk in our guide, and it costs you nine inches of floor.
• Buy the depth back with an arm. A clamp at the back edge cantilevers the panel out over the edge and returns the stand's footprint to the worktop. The arms in our monitor arm guide publish maximum extensions from 18.5 to 24 inches, which is more than enough to put a screen behind the desk line.

The second fix is why so many of the shallow desks in this guide are worth buying. It converts a furniture problem into an accessory problem.

Number 3: clear height under the top

Measure your knee height sitting in the chair you will actually use — floor to the top of your thigh where it meets the desk — and add an inch. Then measure the chair's armrests at their lowest setting, because on most task chairs the arms, not the knees, are what hit the desk.

Compare that against the desk's clear height, which is not the same as its height. IKEA publishes 72 cm (28⅜ in) of clearance under the 77 cm (30⅜ in) KALLAX desk top — a five-eighths-inch top and no rail. A desk with a drawer, a keyboard tray or a front crossbar can lose three to five inches of that, and almost nobody publishes the figure.

Four of five publish nothing, which tells you how this category is sold. Where the figure is missing, subtract the top thickness and any drawer depth from the desk height yourself, and treat the result as an estimate you will confirm on arrival.

Then remember the thing you are about to bolt under there. A cable tray takes its own height out of your knee space: the shallowest tray in our cable guide is 4.5 inches tall and the deepest is 7. On a 29-inch desk that is the difference between 24.5 and 22 inches of knee room.

Number 4: the clearance above the desk

If a shelf, a wall cabinet or a window sill sits above the desk, measure from the desk surface to its underside. Three things compete for that space and people forget all three:

• The monitor. A 27-inch panel on its own stand is roughly 18 to 20 inches tall overall.
• The arm's travel. Arms in our guide publish maximum screen heights from 16 to 20.8 inches at screen center, which means the top of the panel can reach 10 inches higher than that.
• The lamp. A monitor bar clips over the top bezel and adds a couple of inches above the panel; a clamp arm lamp sweeps through a wider arc than that.

Twenty-four inches of clearance above the desk is comfortable for a 27-inch screen on an arm. Below about 20 inches you are choosing between raising the screen and keeping the shelf.

Where the screen should end up

Two published rules are worth holding the tape against once everything is in place.

CCOHS says the reasonable position is the monitor about 15 degrees below the horizontal line of sight — creating a comfortable visual zone of 30 degrees — and that the screen should sit between horizontal and 35 degrees below. It also notes that looking upwards, above the horizontal, is tiring. UCLA puts the top third of the monitor at seated eye level, which lands in the same place from the other direction.

For the keyboard, UCLA's guidance is elbows in a slightly open position — it gives 100 to 110 degrees in its workstation setup and 90 to 100 degrees for the arm and elbow angle — with wrists and hands straight and the keyboard directly in front of your body. In practice that means a desk height near 29 inches for most adults sitting in a chair set to their own leg length.

If you are buying a sit-stand desk, CCOHS adds the standing test: the platform should land at roughly your standing elbow height, with the keyboard and mouse aligned as they are when seated and the monitor still between horizontal and 35 degrees below. Measure floor to elbow standing and compare it against the top of the desk's range — 46.5 inches on the Mount-It! desk in our guide, 51.2 on the VIVO mobile desk.

Two more numbers for cabinets and shelves

If storage is going on the same wall, two clearances decide whether it works.

Above a desk, a shelf wants 16 inches of clear height if you intend to put anything under it other than air, and more if a monitor lives there. A shelf at 14 inches above a 29-inch desk sits at 43 inches from the floor, which is exactly the height a standing person's head arrives at when they lean in.

Beside a desk, a cabinet or drawer unit wants its door swing measured, not its footprint. A 16-inch-wide unit with a hinged door needs 16 inches of clear floor in front of it as well, and in a room where the chair is already using 30 inches of that, the two overlap. IKEA's KALLAX desk avoids the problem by making the storage the leg: its cubes are 13 inches square and open forward with no door at all.

The rule for a desk that publishes nothing

If a product page gives a width and a depth and nothing else — no height, no clearance, no load rating — treat it as a surface of unknown height that may or may not take your chair and may or may not hold a monitor arm. There are enough desks that publish all four for that to be a reason to buy something else.

The same applies to accessories. Of the six cable products in our guide, three publish no load rating at all. Of the six monitor arms, every one publishes an extension and a weight range, which is why that category was the easiest to compare and this one is the hardest.

The ten-minute checklist

1. Wall to the nearest immovable object. Subtract 30 inches for the chair. What is left is the desk depth you can afford, plus any walkway you need.
2. Your monitor's stand depth, and your eye-to-screen distance sitting normally. If it is well under an arm's length, budget for a monitor arm rather than a deeper desk.
3. Knee height and chair armrest height, against the desk's clear height underneath — then subtract the height of any cable tray you plan to fit.
4. Desk surface to the underside of anything above it. Twenty-four inches is comfortable for a 27-inch screen on an arm.
5. Your desk top's thickness at the back edge, where a monitor arm or a clamp lamp will actually grip. Clamp ranges in our guides start at 0.2 to 0.4 inches and stop between 1.97 and 3.5.
6. Floor to elbow, seated and standing, if a sit-stand desk is on the list.

Take those numbers to the compact desk guide, where every pick lists its published depth and height, or to standing desk versus desk converter if you are still deciding between replacing the desk and putting a riser on it.