How to measure your desk before buying any accessory
The 8 measurements that decide whether a monitor arm, tray, riser or hub will fit a small desk: width, depth, thickness, clamp gap, knee space and cable runs.
Almost every bad small-desk purchase is a measurement problem, not a product problem. Take these eight numbers once, keep them in a note on your phone, and every guide on this site becomes a simple fit check instead of a gamble.
The 8 measurements
| # | Measure | Decides |
|---|---|---|
| 1 | Desktop width (left to right) | Monitor size, dual-screen feasibility, shelf length |
| 2 | Desktop depth (front to back) | Viewing distance, arm vs riser, keyboard tray need |
| 3 | Desktop thickness | Whether a C-clamp (monitor arm, tray, headphone hook) can grip at all |
| 4 | Clear gap behind the desk | Clamp space, cable drop, whether the desk can sit flush to the wall |
| 5 | Under-desk height (floor to underside) | Knee clearance once a tray, drawer or keyboard tray is fitted |
| 6 | Under-desk width between legs/frames | Cable tray length, drawer unit fit, footrest space |
| 7 | Distance from desk to the nearest socket | Power strip placement and cable length — the hidden cost of tidy |
| 8 | Monitor VESA pattern + panel weight without stand | Arm/riser compatibility (see the monitor arms guide) |
How to take them honestly
- Measure the desk you have, not the desk in the product photo. Wall skirting, radiators and sloped ceilings steal real centimetres/inches.
- Measure twice for clamp points: many desks have a metal frame or modesty panel exactly where a clamp wants to go.
- Record both units if you shop US and UK stores: cm in the UK, inches in the US, and sellers round differently.
- Photograph the underside and back edge. Half of fit problems are visible in one photo.
Then apply the one-in, measured rule
Before buying, write down: what it replaces, its footprint on (or under) the desk, and the measurement that proves it fits. If you cannot fill in all three, it is a want, not a fix — and on a small desk, wants get expensive fast.
Recommendations
Our picks
Every pick below was checked against this guide's own criteria — the measurements and fit checks above. Research-based: specifications verified against manufacturer and retailer listings, not hands-on tested. Prices are never printed here because they change; the buttons check the current price on Amazon. Last checked: 23 October 2026.
Quick verdict
Picks at a glance
| Product | Key measurements | Best for | Skip if |
|---|---|---|---|
| STANLEY PowerLock Tape Measure, 25 ft (33-425) | Blade: Mylar-coated, with a secure lock that won't creep mid-measurement · Case: Chrome high-impact ABS | Every measurement in this guide, taken once and kept in a note on your phone. | You need measurements finer than a tape reads — for clamp-point thickness, the caliper below is the right tool. |
| NEIKO 01407A Electronic Digital Caliper, 6 in | Construction: Stainless steel · Measures: Inside, outside, step and depth | Thickness, clamp and hardware checks where a millimetre decides fit. | Room-scale runs like desk-to-socket distance — that is the tape measure's job. |
STANLEY PowerLock Tape Measure, 25 ft (33-425)
One tape covers all eight measurements in this guide — and its Tru-Zero end hook is what makes the fiddly ones (desktop thickness for clamps, the gap behind the desk) read honestly rather than approximately.
Will it fit?
- Blade
- Mylar-coated, with a secure lock that won't creep mid-measurement
- Case
- Chrome high-impact ABS
- Model
- 33-425
- Use
- Room-scale and desk-scale measurements
Best for: Every measurement in this guide, taken once and kept in a note on your phone.
Skip if: You need measurements finer than a tape reads — for clamp-point thickness, the caliper below is the right tool.
Prices change — check before you buy.
NEIKO 01407A Electronic Digital Caliper, 6 in
The precision tool for the measurements a tape does badly — desktop thickness at the exact clamp point, clamp jaw openings, VESA and stand hardware — with the inch/mm readout this guide recommends for US/UK shopping.
Will it fit?
- Construction
- Stainless steel
- Measures
- Inside, outside, step and depth
- Resolution
- 0.0005 in / 0.01 mm
- Display
- Large LCD with quick-change unit button
Best for: Thickness, clamp and hardware checks where a millimetre decides fit.
Skip if: Room-scale runs like desk-to-socket distance — that is the tape measure's job.
Prices change — check before you buy.
