Vanity Units by Size: Choosing the Right Width from 300mm to 1800mm

Choosing a vanity unit is much easier when you start with the size.

If you already know how much wall space you have, the width of the vanity should be your first decision. Once you know the right size band, you can narrow the choice by style, installation type, finish and storage layout.

Vanity units are available in widths from compact 300mm cloakroom designs to 1800mm double basin units for larger bathrooms. This guide explains which sizes suit which rooms, how to shop by width and what to do if your space does not match a standard size.

Why Shop by Vanity Unit Size?

The vanity unit has to fit the room before anything else matters.

A finish may look perfect and the storage may be exactly what you want, but if the unit is too wide, too deep or badly placed for the door swing, it will not work properly.

Shopping by size first helps you avoid wasting time on options that will not fit. Once you have the right width, it becomes much easier to choose between wall-hung, freestanding, floorstanding, modern, traditional, painted, oak or marble-top designs.

Vanity Unit Widths at a Glance

Vanity units are available in several common size bands.

300mm to 500mm Vanity Units

Vanity units from 300mm to 500mm are designed for cloakrooms, downstairs WCs and tight ensuites.

These compact units provide a basin and some storage in a small footprint. They are often paired with slim-depth basins, short projections or wall-hung designs to help keep the room feeling open.

A 400mm or 500mm vanity is usually a good choice for many cloakrooms, depending on the wall width, door swing and toilet position.

600mm to 800mm Vanity Units

Vanity units from 600mm to 800mm are some of the most common choices for UK family bathrooms.

They offer a comfortable single basin, useful storage and a balanced footprint. A 600mm vanity is a strong standard option, while a 700mm or 800mm unit can give you more drawer or cupboard space where the room allows.

This size band is a good starting point for main bathrooms and medium-sized ensuites.

900mm to 1200mm Vanity Units

Vanity units from 900mm to 1200mm suit larger bathrooms, master ensuites and spaces where you want more storage.

These widths usually work best as generous single basin units, giving you more counter space and a stronger focal point. Some 1200mm units can include two basins, although a wide single basin may be more practical if storage and surface space matter most.

1400mm to 1800mm Vanity Units

Vanity units from 1400mm to 1800mm are designed for large bathrooms and master suites.

At this size, a double basin layout becomes much more comfortable. There is more room for two basins, better spacing between them and a more useful storage layout beneath.

These larger vanities often become a main design feature, so it is worth planning the mirror, lighting and surrounding furniture at the same time.

Which Vanity Unit Size Suits Your Room?

The best vanity size depends on the room type, wall space and how the bathroom is used.

Cloakrooms and Downstairs Toilets

For cloakrooms and downstairs WCs, look at 300mm to 500mm vanity units.

A compact vanity gives you a practical handwashing basin and storage for small essentials without taking up too much space. In very tight rooms, a wall-hung or slim-depth design can help preserve floor area and standing space.

Always check projection as well as width, as depth is often the limiting factor in cloakrooms.

Small Ensuites

Small ensuites often suit vanity units between 500mm and 700mm wide.

This gives you more basin space than a tiny cloakroom unit while still keeping the room practical. A wall-hung vanity can help the ensuite feel more open, while a floorstanding unit may offer more storage.

Standard Family Bathrooms

Most standard family bathrooms suit 600mm to 800mm vanity units.

This size range provides a comfortable basin and useful storage without overwhelming the room. Choose drawers for smaller everyday items or cupboards for taller bottles and bulkier products.

Larger Bathrooms

Larger bathrooms can often take a 900mm to 1200mm vanity.

This is a good choice if you want more storage, more counter space or a more substantial focal point. A wide single basin is often the most practical option in this range.

Master Bathrooms and Shared Ensuites

Master bathrooms and shared ensuites may suit 1400mm to 1800mm vanity units.

These widths are ideal for double basin designs, especially if two people use the bathroom at the same time. They can also offer generous storage and a more balanced look in a spacious room.

Single or Double Basin by Size

The width of the vanity will help decide whether a single or double basin makes sense.

Under 1200mm

Under 1200mm, a single basin is almost always the better choice.

It gives you more usable basin space, more counter space and more flexible storage. Trying to fit two basins into a narrow width can make both basins feel cramped.

Around 1200mm

At around 1200mm, a compact double basin may be possible, but it is worth considering carefully.

If two people regularly use the bathroom at the same time, it may be useful. If not, a wide single basin will usually give you a better everyday layout.

1400mm and Above

From around 1400mm, double basin vanity units start to feel much more comfortable.

There is more room for two basins, spacing between them and a more balanced storage layout underneath. For a master ensuite or shared bathroom, this is usually the stronger double basin size range.

Remember to Check Depth

Width is important, but depth matters too.

A vanity unit can fit along the wall and still project too far into the room. This is especially common in cloakrooms, narrow ensuites and small bathrooms.

Before ordering, measure from the wall into the room and check how much standing space remains. Make sure the vanity will not block the door swing, toilet access or walkway.

Allow for Door and Drawer Opening

Check that cupboard doors and drawers can open properly.

In tight bathrooms, nearby toilets, radiators, shower screens and doors can all interfere with the vanity. Drawer units are practical, but they still need enough clearance in front.

Use masking tape on the floor to mark the unit depth and door swing if you are unsure.

What If No Standard Vanity Size Fits?

Some bathrooms do not match standard vanity sizes neatly.

You may have a 540mm alcove, a 720mm wall space, a sloped ceiling, boxed pipework or an awkward corner that makes standard sizes difficult.

In these cases, do not force a unit that almost fits. A vanity that leaves an awkward gap or blocks the layout can look wrong for years.

When to Consider Bespoke

A bespoke or made-to-measure vanity unit can be useful when standard sizes do not work properly.

It can be made to suit a specific width, height or projection, helping you use the space more effectively. Bespoke can be especially useful in cloakrooms, period homes, loft conversions and bathrooms with unusual walls or pipework.

Bespoke usually costs more and takes longer than stock furniture, so it is best used when it solves a real fit problem.

How to Measure for a Vanity Unit

Before choosing a vanity size, measure carefully.

Check the full wall width, the depth available from the wall, the door swing, the position of the toilet, radiator and shower, and the location of the waste and water supply pipes.

Leave enough clearance for comfortable use. The largest possible vanity is not always the best choice if it makes the room feel tight.

Vanity Unit Size FAQs

I know my bathroom fits a 600mm vanity. Can I shop by that size?

Yes. If you know a 600mm vanity will fit, start with that size band and then narrow your choice by installation type, style, finish and storage. Still check the depth, door swing and plumbing position before ordering.

What vanity unit sizes are available?

Vanity units are available from around 300mm for compact cloakrooms up to around 1800mm for large double basin bathrooms. Common size bands include 300mm to 500mm, 600mm to 800mm, 900mm to 1200mm and 1400mm to 1800mm.

What size vanity unit is best for a family bathroom?

Most standard family bathrooms suit a 600mm to 800mm vanity unit. This gives you a comfortable basin and useful storage without taking up too much space.

What size vanity unit is best for a cloakroom?

Many cloakrooms suit a 400mm or 500mm vanity unit. In very tight spaces, consider a 300mm to 400mm compact unit, a slim-depth design or a wall-hung option.

What width do I need for a double basin vanity?

Double basin vanity units usually need at least 1200mm, but 1400mm or more is more comfortable. Below 1200mm, a wide single basin is usually the better choice.

What should I do if my wall is between standard vanity sizes?

Measure precisely first. If no standard size fits properly, consider a bespoke or made-to-measure vanity unit. This can help avoid awkward gaps and make better use of the available space.

Find the Right Vanity Unit Size at Plumbworld

Choosing by size is one of the simplest ways to find the right vanity unit.

Start with the width your bathroom can take, then narrow the range by installation type, finish, style and storage layout. Choose 300mm to 500mm for cloakrooms, 600mm to 800mm for most family bathrooms, 900mm to 1200mm for larger spaces and 1400mm to 1800mm for master bathrooms or double basin designs.

Browse Plumbworld’s vanity units by size, cloakroom vanity units, large vanity units, double basin vanity units and bespoke UK-made vanity units to find the right fit for your space.