The clear space you must not take away — bathroom ergonomics
Bathroom design with dimensions: how much clear space you need in front of the WC, basin, shower and bath, and which heights work. A dimensioned floor plan from an interior architect.
Bathroom ergonomics is not about how big the bath is. It is about how much space is left in front of it. That is what decides whether you are irritated twice a day — or never even notice it is there.
The drawing that says it all
Minimum means: still usable. Recommended means: comfortable. For a family with small children we always design to the recommended figures.
What minimum means and what recommended means
The tables carry two numbers, and the two are not the same world.
Minimum = the fitting is usable. One person, one at a time, without rushing.
Recommended = two people fit, you can get in with a child in your arms, and the towel does not hang into the basin.
In practice the difference is 20–25 centimetres per fitting. In a seven-square-metre bathroom that adds up to half a square metre — and that half square metre decides the daily experience.
The four dimensions that really matter
In front of the WC: 53 cm minimum, 76 recommended. Sideways, from the centre line to the wall, 38 minimum, 50 recommended. With the latter you can rest your elbow.
In front of the basin: 53 / 76. For a double basin the width is 150 minimum, 190 recommended — but if the 76 centimetres in front of it is missing, a double basin makes no sense, because you will still step up to it one at a time.
Shower: 66×66 minimum, 90×90 recommended. The 66 exists. It is only good for being able to say there is a shower. The 90×90 is the one you can actually turn around in.
Beside the bath: 53 / 76. If you also use the bath for bathing children, this is not optional — you will be kneeling there.
What the floor plan does not show
A floor plan is horizontal. The daily irritations, though, are vertical:
- Top of the WC seat: 40–45 cm
- Top rim of the basin: 85–90 cm — with a countertop basin the counter sits at 80–85
- Bottom edge of the mirror: 100–110 cm
- Towel rail: 115–125 cm
- Hook: 165–175 cm
These tend to be overlooked because they do not appear on the plan. Yet a basin three centimetres too high will remind you of itself every morning for ten years.
The three most common mistakes
1 · The door opens inwards and takes the space in front of the basin. In a small bathroom an outward-opening or sliding door is the answer. It is a single decision that gives back 60 centimetres.
2 · The radiator sits where the towel rail should be. With a towel radiator, allow for the lowest usable rail to be 115–125 centimetres up — otherwise you bend down every single time.
3 · The fall of the shower floor only comes to light afterwards. The position of the drain channel and the direction of the fall have to be decided before the screed is poured. After that only expensive answers remain. With seamless microcement this is especially true: there the fall is formed in a single plane.
A small bathroom: what changes?
Nothing. The dimensions do not shrink because there is less room — only the decisions get sharper.
What buys space: a wall-hung WC (the cistern inside the wall gives back 15 centimetres of floor), a wall-hung basin (visible floor makes the room read larger), a tray-less shower (no threshold, no visual boundary), and a sliding door. With these the recommended figures can be held even in four square metres.
Frequently asked questions
What is the minimum bathroom size?
With a shower, a WC and a basin, 3.5–4 m² is realistically the size where the recommended clearances can still be held. It can be solved below that as well, but there we are working with the minimum figures, and every centimetre becomes a design decision.
Bath or shower in a small bathroom?
If there is a small child in the family, a bath. If not, a 90×90 walk-in shower, because it leaves more free floor than a 170 bath. As a compromise there is the 160×70 bath with a shower screen — but it does neither job really well.
How much space is needed between the WC and the basin?
Sideways, at least 20 cm between the edges of the two fittings, so that there is somewhere for the paper holder and the towel. From the centre line of the WC to the edge of the basin, 55–60 cm is ideal.
How high should the mirror be?
Its bottom edge at 100–110 cm, and its top edge at least 10 centimetres above the eye level of the tallest member of the household. If there is lighting above the basin, it should not cover the top of the mirror.
If this feels familiar — the bathroom has the size but it still does not come together — see how we work, or read what an interior architect costs.