How do I measure my bathroom space for a replacement walk-in tub?

Measure the finished opening, never the old tub: the length between the finished walls at both the back and the front of the alcove, the width from the back wall to the front edge, and the height from the floor to the bottom of any window sill, with the tile included in every figure. Then note which side the existing drain is on, measure every doorway and hallway on the route in, and compare your numbers with the actual size printed on the spec sheet of the model you are considering rather than the rounded size in its name. How big is a standard bathtub, and how do you measure yours? explains why the alcove length decides what fits; this page is the complete measuring checklist for a replacement walk-in tub, including the measurements most people forget.

The Measurements to Take, in Order

1. Length between the finished walls at the back of the opening. Hold the tape against the finished surface, tile included, because the tub meets the tile and not the framing behind it.
2. Length again at the front edge of the opening. Walls are rarely perfectly square, and the smaller of the two figures is the one to compare with the tub.
3. Width from the back wall to the front edge of the alcove. This is the figure to compare with the tub's actual width.
4. Height from the floor to the bottom of any window sill, ledge or soffit above the space. A laid-down tub stands 21 inches tall, while a seated model such as the Elite stands 35 inches, so this figure can rule a model in or out.
5. Ceiling height, if you are considering a shower combination model or want to use the tub as a shower too.
6. The drain location. Stand facing the tub and note whether the existing drain is on the left or the right.
7. The distance from the tub space to your water heater. It is not a fit measurement, but it helps your plumber plan the supply lines.
8. The clear floor in front of the tub. If an outward swing door interests you, plan on at least 20 inches of clear floor space in front of the tub so the door can open fully without hitting a toilet or vanity.
9. The route in. Measure the bathroom doorway and every doorway, hallway and turn between the delivery point and the bathroom, because the crate has to get through.

What these comparisons mean in practice: the length and width tell you which footprints are candidates, the height tells you whether a seated tub clears the window, the drain side tells you which door configuration to order, the clear floor tells you whether an outward swing door is realistic, and the route tells you whether delivery day will go smoothly. If any one of them is tight, that is the number to send the team before you order.

Why the Size in the Model Name Is Not the Number to Use

The size in a model name is a rounded figure. The Ella Petite is marketed as a 28 inch tub, but its actual size is 27.5 inches wide by 52 inches long by 35 inches high, and the Ella Elite's actual size is 30 inches wide by 52 inches long by 35 inches high. Always compare your measurements with the actual size on the spec sheet, which you can download from the product page, not with the name on the brochure.

Ella's standard sizes run from a compact 26x45 up to a 32x72 laid-down model. The most common footprint is 30 inches wide by 52 inches long, and tubs are also offered in 32x52, 38x52, 30x60, 30x55, 28x52, 27x60 and 26x45 inch sizes, with the Monaco at 32 by 53 or 32 by 52 inches and a transfer-style tub at 60 by 30 inches. Walk-In Tub and Shower Base Sizes and How to Measure for Fit lists them alongside the shower base options.

A tub does not have to fill the alcove on its own. Ella tubs shorter than 60 inches include an extension panel that closes the gap between the tub and the end wall, and the panel can be cut down to size, so a 52 inch model goes into a 60 inch alcove and still looks built in. That is why the compact 52 inch models are the usual starting point when a shower stall, which is often shorter and narrower than a tub alcove, is being replaced.

The Drain Decides the Door Side

On every Ella walk-in tub the door and the drains are on opposite sides. A right-side door tub has its drains on the left, and a left-side door tub has its drains on the right, sides as you face the tub. So the drain you noted is not just a plumbing detail: it tells you which door configuration to order, and therefore whether the door will open toward the open side of your bathroom or toward a wall. If you want the door on the same side as the existing drain, your plumber will need to relocate the drain, which is a conversation to have at the site visit rather than after the tub arrives.

Measure Yourself as Well as the Room

The seat and the depth of water have to suit the bather, so take a second set of measurements. Sit in a straight chair facing a wall and measure your hips, your shoulders, the length from the top of your head to your feet while seated, and your seated torso length. Compare those against the seat widths, interior lengths and seat-to-overflow figures on the spec sheets of the models that fit your room.

The video shows the three factors that determine soaking depth in a seated tub: the measurement from the top of the seat to the center of the overflow, the length of the seat, and the interior length of the tub. Your own size changes where the water lands on your body, which is why the seated measurements above matter as much as the room. If stretching out matters more than sitting, the laid-down tubs come in 30x60 and 32x72 inch sizes and stand 21 inches tall, and Laid-Down Walk-In Tub Dimensions and Fit runs the space check for them.

The Floor, the Gap and the Site Visit

Floors are rarely level. The panel that covers the space between the front panel of the tub and the floor is two inches wide and usually comes installed on the tub; if the tub is set lower than its standard height, the gap is narrower and the panel is trimmed to the smallest measurement taken at both ends and the middle, as described in Gap Between the Front Apron and the Floor: The Two Inch Toe Kick Panel and When to Trim It. Knowing that now saves a surprise on installation day.

Your own measurements get you to a shortlist, and a contractor's visit confirms the fit. As with the Shower Builder Tool, where a contractor visits in person to measure the space and finalize the installation details after you have explored a design, your installer will confirm the opening, the doorway, the drain and the door swing before anything is ordered. If you would like a second set of eyes on your numbers first, send your alcove length, width and height, your drain side and your doorway widths with the model you are considering through ellasbubbles.com/support, or call your Ella dealer or the team at (800) 480-6850.

Watch: How to Measure the Soaking Depth in Your Walk-In-Tub | Ellas Bubbles with chapters and a full transcript.

Related Guides

• Walk-in tub dimensions by model: exterior sizes, seat widths, and door types
• Will it fit through my doorway? How to measure your home for a walk-in tub
• Will it fit my alcove? Extension panels, end panels, and 60 inch spaces

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