Length matters more than width
Walk-in trays come in common lengths such as 1200, 1400 and 1600 mm, and widths around 700 to 900 mm. The length decides how far the head sits from the open end. On a short tray, the spray reaches the gap and water ends up outside; on a longer one, it falls back into the tray before it gets there.
Width decides comfort. A narrow tray can feel tight for turning around or for washing hair, and it leaves less room for a seat if one is wanted later.
Where the head goes
Put the shower head at the closed end, furthest from the entry, with the spray aimed away from the opening. A fixed overhead rain head drops water straight down and splashes less than an angled handset, but a handset on a riser rail is easier for rinsing and for anyone who sits.
The valve position matters as much. Ideally you can reach the controls from outside the spray, so you do not stand under cold water waiting for it to warm up.
Screens and the open end
Most walk-in showers use one fixed glass panel along the long side, sometimes with a short return panel or a hinged deflector at the end. The panel should cover a good part of the tray length; too short and the room gets wet.
The clear space you walk through also needs to be wide enough to step in comfortably, and in an accessible bathroom wide enough for a frame or wheelchair, which may mean choosing a level-access floor rather than a tray altogether.
Measuring your room
Measure the full length of the wall where the shower would go, and how far it sits from the door and the toilet. Mark the door swing, because a door that opens into the shower's entry path is awkward and can clip the glass. Note where the soil pipe and existing waste leave the room.
Allow room to stand and dry outside the shower as well. A walk-in that fills the room edge to edge often feels cramped once you step out.
When the room is too small
If the room cannot take a tray long enough to control splashing, there are other options: a standard enclosure with a door, a shorter walk-in with a hinged return panel, or, in some rooms, a wet room where the whole floor is waterproofed so splashing matters less. Our walk-in shower options guide compares the types, and we will tell you honestly if a walk-in is not the right fit for your space.
Getting it sized properly
Send photos of the room and rough measurements of the wall, the door position and the current bath or shower. We fit walk-in showers as part of bath to shower conversions and full refits, and we size the tray and screen to the room rather than the other way round. Quotes are free and fixed in writing, and we aim to reply within 24 hours.