Measure before buying
Chair and desk measurement instructions
Product dimensions only become useful when they are compared with your body, equipment and room. Use a tape measure, a firm chair, removable floor tape and a second person where possible.
How to measure for an office chair
Take body measurements while sitting in a neutral position rather than standing. Wear normal work clothes and shoes, keep feet supported and repeat any measurement that changes significantly.
- 1
Seat height
Sit with your feet flat in the shoes you normally wear. Measure vertically from the floor to the crease behind your knee. Look for a chair whose seat-height range includes that figure, then test with thighs roughly level and no pressure behind the knees.
- 2
Seat depth
Sit against a wall or firm backrest and measure from it to the back of your knee. A usable chair seat should support most of the thigh while leaving roughly two to four finger widths behind the knee. Check whether the seat pan slides if your measurement falls outside a fixed seat depth.
- 3
Hip width
Sit naturally and measure across the widest point of your hips or thighs, then add several centimetres for movement and clothing. Compare that figure with the usable width between the arm supports, not the chair’s total external width.
- 4
Armrest height
Relax your shoulders and bend your elbows near 90°. Measure from the compressed seat surface to the underside of your elbow. Armrests should adjust near that height and fit under the desk when you want to move closer.
- 5
Back and lumbar position
Measure from the seat surface to the inward curve of your lower back. Product listings rarely give a perfect lumbar-height range, so prioritise an adjustable support or a chair you can return after a careful seated trial.
How to measure for a home office desk
Measure the room at the height where the desktop and chair will actually sit. Floors, alcoves and walls are not always square, so take width and depth readings at more than one point and plan around the smallest usable figure.
Check 1
Available footprint
Measure wall-to-wall width at desktop height, then subtract skirting boards, radiator valves, curtains and anything that projects into the space. Measure depth from the wall to the nearest obstruction and mark the result with removable tape.
Check 2
Working height
While seated correctly, measure from the floor to the underside of your relaxed elbow. A keyboard surface close to that height helps keep shoulders relaxed. For a fixed desk, check whether chair adjustment and a footrest can bridge a small mismatch.
Check 3
Usable depth
Measure the monitor stand or arm, keyboard, wrist space and cable bend rather than relying on the desktop’s headline depth. Leave a safe rear margin for plugs and enough eye-to-screen distance for the chosen monitor.
Check 4
Chair movement
From the front edge of the desk, allow space for the chair base, rolling back and standing up. Around 80–90 cm is a useful planning allowance behind a frequently used chair; doors and walkways may require more.
Check 5
Under-desk clearance
Check clear width and height between drawers, legs, crossbars and cable trays. Compare these with your knees, chair arms and preferred sitting position. A wide desktop can still have a surprisingly narrow usable opening.
Check 6
Delivery route
Measure the tightest doorway, stair turn and lift before ordering a large desktop or assembled chair. Record package dimensions separately from product dimensions when the retailer provides both.
Record these numbers
- Maximum room width and depth
- Target seated elbow and desktop height
- Monitor width, stand depth and viewing distance
- Usable under-desk opening
- Chair seat range and width between arms
- Clearance behind the chair and delivery-route limits
Common measuring mistakes
- Using total chair width instead of the space between armrests.
- Ignoring skirting boards, window handles and radiator controls.
- Planning monitor distance without the depth of its stand.
- Measuring an empty room but forgetting the open door and chair movement.
- Assuming a sit-stand desktop remains clear at every height.
Turn your measurements into a shortlist
Use the desk calculator first, then answer the builder with the closest width and depth bands.