A desk fits only when the equipment, knees, chair, cables, and person can all use it. The closed furniture footprint is just one part of a workable small-room office.
Lay out the real equipment
Measure the laptop, monitor stand, keyboard, mouse area, lamp, and any paper space used at the same time. Shelves, risers, drawer boxes, and frame rails can reduce the usable desktop from the advertised width and depth.
Check knee and foot room
Record the clear width and height beneath the desk and any bars, drawers, or shelves that reduce it. A narrow desk may fit the wall but force an uncomfortable off-center posture.
Add the chair footprint
Measure the chair at its widest point, the depth while occupied, and the pullback needed to sit and stand. Preserve the room's main walkway and the movement of nearby doors, beds, and drawers.
Plan monitor distance and height
A very shallow surface may place the screen too close or leave no room for a keyboard. Choose a layout that supports comfortable viewing and input positions, and consider a suitable arm only when the desk and mounting system support it.
Route power and data safely
Map the outlet, plug depth, power strip placement, charging cables, and the path to equipment. Keep cords out of chair wheels and walkways, follow electrical requirements, and do not pinch cables behind folding parts.