Buying a vanity without measuring properly is the most common reason people return bathroom furniture. A unit that's 50mm too wide blocks the door; one that's 30mm too deep hits the toilet. This guide covers the six dimensions you actually need before ordering — plus the two checks most people skip.
Tools you need
You don't need anything fancy: a 5-metre tape measure, a pencil, a notebook, and a spirit level if you want to check wall straightness. Ten minutes is enough to measure a standard UK bathroom properly.
The six dimensions to record
Measure each of these in millimetres (not inches — almost every UK bathroom product is spec'd in mm). Round down rather than up so you don't over-promise the space.
- Available wall width — floor to counter height, from wall to wall along the run where the vanity will sit. If there's a skirting board, measure above it.
- Wall-to-nearest-obstruction — shortest distance from the wall to the toilet, door frame, radiator, or anything that sticks into the space.
- Depth — how far the unit can project into the room without blocking a door swing, towel rail or circulation route. A standard UK vanity is 400–500mm deep; compact units are 300–380mm.
- Ceiling height and tile/skirting height — useful if you're considering a wall-hung unit that needs to clear the skirting.
- Plumbing centre — horizontal distance from the corner wall to the centre of the existing waste pipe. This is the critical number: a unit whose basin is 100mm off-centre from the waste needs the pipe moving or a flexible connector bending further than it should.
- Door clearance — open the bathroom door fully and measure how close it comes to the vanity position. Add a 10mm safety margin.
Match the vanity to the plumbing, not the other way around
Moving waste pipes is expensive (plumber time + pulling up flooring). It's almost always cheaper to buy a vanity whose basin aligns with your existing waste than to retrofit the waste to a pretty vanity. When comparing units, check:
- Whether the waste is central in the basin, or offset (some designer basins have the waste to one side)
- Whether the unit has a bottle trap or a P-trap — bottle traps sit inside the cupboard and take more depth
- Whether the basin supports your tap style — some slim basins don't have a tap hole; you'll need a wall-mounted tap instead
Wall-hung vs floorstanding
Two things to check if you're considering a wall-hung unit:
- The wall itself — stud walls need strong noggins behind the plasterboard to carry the load. Solid masonry walls are usually fine.
- Skirting board — a wall-hung unit usually sits above the skirting. If you have 150mm skirting, a 300mm-tall wall-hung unit starts at 450mm off the floor, which may look too high.
Floorstanding units avoid these issues but take up more visible floor space, which can make small bathrooms feel tighter. See our full range of bathroom vanities for both styles.
Two checks most people skip
1. The spec sheet overhang. Countertop basin units often list “overall width” of the cabinet but the basin overhangs by 10–30mm on each side. Always read both numbers.
2. The carry-in route. A 1200mm vanity in one piece may not come up a tight staircase or through a narrow loft hatch. Check the packed dimensions (usually in the product description) against your hallway, stairs and bathroom door.
Quick reference: common UK vanity sizes
- Cloakroom / compact — 300–450mm wide, 300–400mm deep. Fits where a pedestal basin currently sits.
- Standard ensuite — 500–600mm wide, 400–450mm deep. Single-door cabinet underneath.
- Main bathroom single — 700–900mm wide, 450–500mm deep. Drawer or two-door cabinet.
- His-and-hers / twin basin — 1200–1500mm wide. Needs a larger bathroom (typically 5m²+).
Ready to order?
Once you have the six measurements and the plumbing-centre note, our vanity range is easy to filter by width. If you're unsure, contact our team before ordering and we'll double-check dimensions against the spec sheet for you. All vanities ship with free standard UK delivery, and bulky units arrive kerbside with full tracking.
