Thinking about a barrier-free or low-threshold shower? It starts with the right measurements. This simple step-by-step guide shows you how to measure your bathroom so you can choose the right shower pan, avoid surprises, and make your conversion go smoothly.
Good measurements = better quotes, better fit, and fewer headaches.
Grab a tape measure, a notepad, and a helper if possible. We will walk you through it.
Why Accurate Bathroom Measurements Matter
When you convert a tub to a walk-in or install a barrier-free shower pan, every inch counts. A small error can mean reordering a base, moving plumbing twice, or fighting with walls that are just a little off.
At Showers4Less, we work with Aging Safely Baths to supply factory-ready shower pans. They are made in the USA, come in standard and custom sizes, and carry a 30-year manufacturer warranty. But we still need good numbers from you so everything fits the way it should.
With correct measurements you can:
- Select the right size barrier-free or low-threshold base.
- Match the drain to your existing plumbing or plan a move.
- Ensure enough room for mobility devices and doors.
- Reduce labor time and installation surprises.
Tools You Will Need
- Tape measure (at least 10–12 feet).
- Notepad or printed measurement sheet.
- Pencil or pen.
- Small level (optional, but helpful).
- Flashlight for dark corners.
- A helper if possible, especially in tight spaces.
That is all most people need to complete the basic measuring steps.
Quick Overview: What You Will Measure
1. Width
Wall-to-wall distance where the shower will sit.
2. Depth
Front-to-back distance from the back wall to where the threshold will be.
3. Height & Obstacles
Ceiling height, window locations, knee walls, and soffits.
4. Drain Location
Exact drain position from each wall.
5. Door & Entry Space
Clearance for glass doors or curtains and walking space.
6. Floor Height
Difference between bathroom floor and subfloor, when known.
7. Future Features
Space for seats, grab bars, and niches.
Step 1: Measure the Back Wall Width
This is the most important dimension. It tells us how wide the shower pan should be.
Tip: Use a 3D-style diagram that shows the back wall and side walls, but no text inside the graphic.
- Measure from one finished side wall to the other at the back of the shower space.
- If your old tub is still in place, measure from drywall edge to drywall edge above the tub.
- Measure again near the middle and near the front, because walls are not always perfectly square.
- Write down the smallest number. That is usually the safe size to use.
Step 2: Measure the Depth of the Shower Area
Depth is the front-to-back distance that determines how much room you will have to move and turn.
Use an angled 3D diagram that shows the floor depth from the back wall toward the bathroom.
- Measure from the back wall to the point where the new threshold will be.
- If you are replacing a tub, measure from the back wall to the front edge of the tub deck.
- Check for obstructions like baseboard heaters, doors, or cabinets.
- Record the smallest depth if you get different numbers in a few spots.
Step 3: Measure the Drain Location
Drain position is critical when you want to avoid moving plumbing. You will measure from the studs or finished walls.
A 3D diagram from above can show a circle for the drain with arrows to each wall, with no words.
- Locate the center of the existing drain.
- Measure from the drain center to the back wall. Write this number down.
- Measure from the drain center to the side wall (left or right). Write this down as well.
- If the tub is still in place, you may need to remove the drain cover or look from below where possible.
We will use these two numbers to match a compatible shower pan or design a custom base.
Step 4: Measure Ceiling Height and Check for Obstacles
Next, make sure there is enough vertical space for shower walls and fixtures.
- Measure from the bathroom floor to the ceiling above the shower area.
- Note any soffits, angled ceilings, or beams that lower part of the ceiling.
- Check for windows in the shower wall. Measure their height and distance from each corner.
- Look for plumbing chases or bump-outs that may reduce usable width.
Good to know: Many shower wall systems can be cut to fit under lower ceilings. Custom systems can be designed around windows and kneewalls.
Step 5: Measure Entry, Door Swing, and Walk Space
Barrier-free and low-threshold showers feel more open. But we still want to double-check that you have enough room to step in, turn, or roll in with a walker or wheelchair.
A simple angled diagram can show the shower opening and a clear floor area in front, with no text in the art.
- Measure the open floor space in front of the shower area from the threshold out into the bathroom.
- Measure side-to-side space in front of the entry.
- If you plan a swinging glass door, note which way it will swing and check for conflicts with toilets, vanities, or walls.
- If a curtain will be used, make sure the rod and rod return will not hit anything.
Step 6: Check Floor Height and Threshold Goals
Now think about how low you want the entry to be. This helps us recommend a barrier-free pan or a low-threshold pan that lines up with your floor.
Basic guidelines:
- If you want near-zero entry, a barrier-free or very low beveled threshold is ideal.
- If you have thick tile, a slightly higher squared threshold may align better.
- Aging Safely Baths pans can go as low as about 0.5" threshold height in some models.
If you know the subfloor situation or are removing the entire floor, tell us. Our team can help you match the best threshold style for your situation.
What to Send Us for a Fast, Accurate Recommendation
Once you have your measurements, you are ready to reach out. You do not need a perfect drawing. Simple notes work fine.
Helpful details to share with Showers4Less:
- Width and depth of the shower area.
- Drain location from each wall.
- Ceiling height in the shower area.
- Any windows or obstacles in the shower walls.
- Flooring type now and planned flooring type after the remodel.
- Who will use the shower (mobility devices, caregivers, seniors, kids, etc.).
From there, we can recommend a barrier-free or low-threshold shower pan size and style that fits. We can also help you choose wall systems, seats, and accessories.
FAQ: Measuring for a Shower Conversion
They do not need to be perfect, but closer is better. We usually ask for two or three measurements in both width and depth so we can see if the walls are out of square. If something looks off, we will ask a few follow-up questions before you order.
You can measure with the old tub still in place. It is better to measure from finished walls whenever possible. If demolition has not started yet, we can work with approximate numbers and adjust after the tub comes out.
That is very common. Many homes are not exactly 60 inches wide or 36 inches deep. Aging Safely Baths offers custom-sized shower pans, and we can also use wall panels that are trimmed to fit your space.
Yes. Tell us who will use the shower and what your goals are. We can walk you through ADA-style setups, roll-in shower options, and non-compliant but still very safe configurations that fit your bathroom and budget.
You can ask a contractor, handyman, or family member for help. Some customers have their plumber or installer send us the measurements directly. If you prefer, we can also review photos and sketches and walk you through the process step by step.