How to Measure for a Shower Enclosure – Complete Guide
Measuring for a new shower enclosure isn't difficult, but it does need to be accurate.
A few millimetres can make a difference, particularly when you're fitting an enclosure between existing walls, onto an existing shower tray or into a bathroom where the walls aren't perfectly straight.
The golden rule?
Measure carefully, measure in several places — and measure before you order.
In this Allbits Bathroom Academy guide, we'll take you through how to measure for a shower enclosure, what dimensions you need, why adjustment ranges matter and some of the common measuring mistakes to avoid.
If you're still deciding which type of enclosure would work best in your bathroom, start with our Complete Shower Enclosure Buying Guide.
INTERNAL LINK: Add link to The Complete Shower Enclosure Buying Guide once its final live URL is available.
What Do I Need to Measure a Shower Enclosure?
You don't need an enormous collection of tools.
For most bathrooms you'll need:
- A good-quality tape measure
- A spirit level
- A pencil and notepad
- Your phone for taking reference photographs
- The technical dimensions of the enclosure you're considering
A second pair of hands can also be useful when measuring larger openings.
And while we're talking tape measures, this is not the occasion for "it's roughly 900mm."
Roughly is the enemy of shower enclosures.
Are You Measuring for a New Shower Tray or an Existing One?
Before taking measurements, establish exactly what you're working with.
There are two common situations:
New Bathroom Installation
If you're installing a new shower tray and enclosure together, you have more flexibility.
You can choose a tray and enclosure combination suitable for the available space, provided you've allowed enough room for installation, access and the shower door to operate.
Take a look at the Allbits Shower Enclosures & Doors collection alongside our Shower Trays collection when planning your combination.
Replacing an Existing Shower Enclosure
If you're keeping your existing shower tray and replacing only the enclosure, accurate measurement becomes particularly important.
Don't simply order an enclosure based on what you believe the old one was.
Measure the actual installation area and tray.
Older trays and enclosures may not correspond exactly with today's nominal product sizes.
Step 1: Identify the Shape of Your Shower Area
Before worrying about individual dimensions, identify the type of enclosure you're measuring for.
Common configurations include:
- Square
- Rectangular
- Quadrant
- Offset quadrant
- Corner entry
- Shower door and side panel
- Recess shower door
- Walk-in shower
The shape determines which measurements you'll need.
If you're still choosing, browse the Allbits Shower Enclosures & Doors collection to compare the different configurations available.
Step 2: Measure the Width
Measure the available width where the enclosure will be installed.
If you're fitting between two walls, don't take just one measurement.
Measure the opening at approximately:
- Tray level
- Mid-height
- Near the top of the proposed enclosure
Write down all three measurements.
Why?
Because bathroom walls aren't always perfectly parallel.
A wall can look completely straight while gradually moving inward or outward as it rises.
If your measurements differ, the enclosure's adjustment range becomes extremely important.
Step 3: Measure the Depth
Next, measure how far the enclosure can project into the room.
For a corner enclosure, measure from the back wall towards the front edge of the proposed showering area.
Again, take measurements carefully and check for anything that could interfere with the enclosure.
Look for:
- Toilets
- Basins
- Vanity units
- Radiators
- Heated towel rails
- Doors
- Windows
- Pipe boxing
- Skirting or wall projections
You need enough room not only for the enclosure itself but also to get into it comfortably.
Step 4: Measure the Shower Tray
If you're installing an enclosure onto an existing tray, measure the tray carefully.
Measure along the finished edges where the enclosure will actually sit.
You'll need to establish:
- Overall shape
- Width
- Depth
- Position against the walls
- Usable mounting area around the tray edge
If you're replacing both components, choosing compatible products from the outset is considerably easier.
Browse Shower Trays at Allbits
Step 5: Check Whether the Walls Are Plumb
Here's one that can catch people out.
A wall can be perfectly straight from left to right but still lean slightly inward or outward vertically.
Use a spirit level to check whether the walls are plumb.
Small variations can often be accommodated by the adjustment available within an enclosure's wall profiles.
Larger variations may need to be addressed before installation.
This is one reason you should always check the actual manufacturer's adjustment range rather than relying purely on the nominal enclosure size.
What Is a Shower Enclosure Adjustment Range?
This is one of the most important things to understand when buying an enclosure.
A shower enclosure sold as 900mm, for example, doesn't necessarily mean that every part of the installed enclosure measures exactly 900mm.
Many enclosures incorporate an adjustment range within their wall profiles.
This allows the installer to compensate for minor variations in the walls and installation area.
For example, an enclosure might be described as a nominal 900mm model but have a manufacturer-specified fitting range around that dimension.
Always use the adjustment range stated for the exact enclosure you're purchasing.
Don't assume two different 900mm enclosures will have identical adjustment.
How Do I Measure for a Quadrant Shower Enclosure?
Quadrant enclosures are designed for corner installations and have a curved front.
You'll normally need to establish the dimensions along both walls from the corner.
For a standard quadrant, these dimensions will typically be equal.
For example:
800mm x 800mm
or
900mm x 900mm
However, don't assume the existing tray is a particular size simply because it looks like one.
Measure both sides.
You can compare suitable models in the Allbits Quadrant Shower Enclosures collection.
For more help choosing this style, read our Ultimate Guide to Quadrant Shower Enclosures.
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How Do I Measure for an Offset Quadrant Shower Enclosure?
An offset quadrant has one side longer than the other.
You therefore need to measure both dimensions.
For example:
1000mm x 800mm
or
1200mm x 900mm
But there's another important consideration.
Left Hand or Right Hand?
Some offset quadrant enclosures and trays have a specific orientation.
Don't rely on memory or assume that "left hand" and "right hand" will mean what you expect.
Check the manufacturer's diagram for the exact product and compare it with your proposed installation.
This is definitely a measure twice, order once moment.
How Do I Measure for a Shower Door in a Recess?
If the shower will sit between three walls, with only a door across the front, measure the opening carefully.
Take the width at:
- Tray level
- Mid-height
- Near the top
If those measurements aren't identical, note the smallest and largest measurements and compare them with the manufacturer's adjustment range.
Also check that the walls are plumb.
Different door types suit different spaces, including:
- Sliding doors
- Pivot doors
- Hinged doors
- Bi-fold doors
You can compare these styles in the Allbits Shower Enclosures & Doors collection.
Don't Forget the Shower Door Opening
Finding an enclosure that physically fits the available space is only half the job.
You also need to make sure you can open it.
For hinged and pivot doors, check the manufacturer's door-opening dimensions and consider everything immediately outside the enclosure.
Could the door hit:
- A basin?
- Vanity furniture?
- A toilet?
- A radiator?
- A towel rail?
- The bathroom door?
Sliding and bi-fold doors can be particularly useful where external clearance is limited because they don't require the same outward opening space.
Allbits Tip: When planning a small bathroom, mark the approximate door swing on the floor. It's a simple way to spot potential clashes before you buy anything.
Check the Entry Width Too
The overall width of an enclosure isn't the same thing as its entry width.
This is particularly important with sliding and quadrant enclosures.
A 1200mm-wide shower enclosure doesn't necessarily provide anything close to a 1200mm opening.
Check the manufacturer's specification for the actual entry width and make sure it will be comfortable for the people using the shower.
Measuring for a Walk-In Shower
Walk-in showers require slightly different planning because you're usually dealing with one or more fixed glass panels and an open entrance.
Consider:
- Available panel width
- Overall showering area
- Entrance width
- Shower tray or wet-room area
- Position of the shower head
- Direction of water spray
- Nearby furniture and sanitaryware
Bigger isn't automatically better when it comes to the entrance.
You want comfortable access while retaining enough screening to help control splashing.
Walk-in shower panels are available within the Allbits Shower Enclosures & Doors collection.
Should I Measure Before or After Tiling?
This is an important one.
For the most accurate final enclosure measurement, you need to consider the finished wall surfaces.
Tiles, wall panels and other finishes change the available dimensions.
If you're measuring before the bathroom is finished, allow for the thickness of the planned wall covering and adhesive system.
For installations where the final dimensions are critical — particularly recess installations — taking final measurements once the walls are finished can reduce the risk of ordering the wrong size.
Don't Forget the Height
Width and depth get most of the attention, but check the enclosure height too.
Make sure there are no obstructions such as:
- Sloping ceilings
- Low beams
- Windows
- Shelves
- Decorative features
This is particularly important in loft bathrooms and rooms with unusual ceiling shapes.
Also remember that the overall installation height may include the shower tray plus the enclosure.
What If My Measurements Are Slightly Different?
Don't panic.
Slight differences between measurements are common, particularly in older properties.
This is precisely why many shower enclosures include adjustable wall profiles.
The important thing is to compare your measurements against the manufacturer's stated fitting or adjustment range.
If your measurements fall outside that range — or you're unsure — don't simply hope it'll fit.
Check before ordering.
A five-minute query is much easier than discovering you've got the wrong enclosure halfway through installation.
Common Shower Enclosure Measuring Mistakes
A few mistakes crop up time and again.
Measuring Only Once
Take several measurements, particularly between walls.
Assuming the Tray Size
Measure it. Don't guess from appearance.
Ignoring the Adjustment Range
The nominal product size and actual fitting range aren't necessarily the same thing.
Forgetting About Tiles
Finished wall dimensions matter.
Ignoring Door Clearance
An enclosure can fit perfectly while its door hits the basin.
Not ideal.
Forgetting Left- and Right-Hand Options
Particularly important with offset configurations.
Measuring Wall to Wall Instead of the Installation Position
Think about where the enclosure profiles will actually sit.
Ordering Before Checking the Manufacturer's Technical Information
Always compare your measurements with the specifications for the exact product you're buying.
Shower Enclosure Measuring Checklist
Before ordering, make sure you've checked:
- Shower enclosure shape
- Width at several heights
- Depth
- Existing shower tray dimensions
- Wall plumb
- Finished wall surfaces
- Manufacturer adjustment range
- Enclosure height
- Door opening direction
- Door clearance
- Entry width
- Left/right-hand orientation where applicable
- Nearby sanitaryware and furniture
- Manufacturer technical dimensions
And then?
Measure it once more.
Yes, we're nagging.
You'll thank us later.
Frequently Asked Questions
Do shower enclosures have to be exactly the same size as the tray?
The enclosure and tray must be compatible, but you shouldn't make assumptions based solely on their nominal sizes. Always check the manufacturer's fitting dimensions and adjustment range for the specific enclosure and tray you're considering.
Where do you measure a shower enclosure from?
The correct measuring points depend on the enclosure configuration and manufacturer's instructions. Generally, you'll need accurate dimensions across the intended installation area and, for corner enclosures, along both walls. Existing trays should be measured where the enclosure will actually be installed.
What happens if my bathroom walls aren't straight?
Minor variations may be accommodated by adjustable wall profiles, depending on the enclosure. Check the manufacturer's adjustment range. More significant irregularities may need correcting before installation.
Can I measure an old enclosure and buy the same size?
It's safer to measure the actual tray and installation area rather than relying on the dimensions of the old enclosure.
Should I measure before buying the shower tray?
Yes. Measure the available bathroom space before selecting either the tray or enclosure. If you're replacing both, choose compatible products and check all technical dimensions before ordering.
Is it better to measure after tiling?
Where final dimensions are critical, measuring the finished installation area after tiling or wall finishing gives you the most accurate dimensions. If products need to be selected beforehand, account carefully for the finished wall build-up and follow the manufacturer's installation information.
Ready to Choose Your Shower Enclosure?
Once you've taken accurate measurements, choosing the right enclosure becomes considerably easier.
At Allbits Plumbing Supplies, you can compare different enclosure styles, door configurations, glass options and shower trays to find a combination that works with your bathroom.
Shop Shower Enclosures & Doors at Allbits
Shop Quadrant Shower Enclosures at Allbits
And if you're unsure about your measurements or whether a particular enclosure is suitable, check before you order. Getting the dimensions right at the beginning can save a great deal of trouble later.