How do I measure the soaking depth of a walk-in tub?

Measure soaking depth from the top of the seat to the center of the overflow opening, because the overflow caps the water level and that is where a full tub stops rising. Take two more figures with it, the length of the seat and the interior length of the tub, and then compare the seat-to-overflow number with your own seated torso rather than with your height. What Is Soaking Depth on a Walk-In Tub? defines the term and lists each model's figure; this page is the step-by-step for taking the measurement yourself and reading it.

The Three Measurements, in Order

Both Ella measuring videos on this page show the same three factors, and they are the whole method. The soaking depth of a walk-in tub is determined by the interior length of the tub, the length of the seat, and the depth from the top of the seat to the center of the overflow drains, and the bather's own size then sets the result.

1. Seat to overflow. Stand a tape upright on the seat surface and read it at the center of the overflow opening. This is the number called soaking depth, or water depth when seated, on a spec sheet.
2. Seat length. Measure the seat from its front edge to the backrest. It tells you how much of the interior is seat and how much is footwell.
3. Interior length. Measure inside the tub from end to end. More interior length lets you stretch out and settle lower; a shorter interior keeps you more upright.

Only the first figure is a depth. The other two shape how you sit in that depth, which is why a spec sheet that prints all three, as the Deluxe does with a 47 1/2 inch interior length, a 15 1/2 inch seat length and a 19 inch seat-to-overflow depth, tells you more than a single number.

Measuring a Tub You Can Reach

If you are standing at a tub, in a showroom, in someone's home or at your own installed unit, measure it empty.

• Find the overflow, not the rim. Water rises to the overflow opening and then runs out, so the rim height says nothing about how deep you will sit. The common mistake is to measure to the top of the wall and expect that much water.
• Measure from the seat, not the floor, on a seated tub. The published figure on every seated Ella tub is seat to overflow.
• On a LayDown tub, measure from the floor of the tub to the overflow, because there is no seat. The LayDown 30 by 60 spec sheet uses the same template as the seated tubs and prints a seat line anyway; ignore it. That tub measures 15 3/4 inches from its floor to the overflow, a figure the team has confirmed the water actually reaches, on a flat 46 by 20 inch floor that widens to about 53 by 25 1/2 inches above the floor.
• If you are comparing against the tub you already have, a standard bathtub is the reference row in Ella's published size comparison at a soaking depth of about 11 inches, described by the depth of its water rather than by its wall.

Two filling rules go with the measurement. Fill to the overflow for the deepest soak, and never fill above the center of the drain handle, since anything that rises above the overflow is carried away in any case. How Deep Is the Water Really in a Walk-In Tub? works through the LayDown case and the rim versus overflow confusion in more detail.

Measuring Yourself so the Number Means Something

There is no soaking depth calculator, and your own build is what turns the seat-to-overflow figure into a feeling. A taller bather sits higher in the water than a shorter one in the same tub, and a long torso feels a shallower soak than a short one. Ella's measuring method does not ask how tall you are. Sit in a sturdy chair facing a wall, relaxed, and take these measurements:

1. Across your hips while seated. The tub seat must be wider than this number.
2. Across your shoulders while seated. This checks against the interior width.
3. From the top of your head to your feet while seated. This is compared with the interior length.
4. From the seat surface to your shoulders. This is your seated torso length, and it is the figure you set against seat to overflow to see where the water will land on your body.

Then compare: seat width against hips, interior length against seated head-to-feet, and seat-to-overflow against seated torso. Fit, not a weight limit, is what decides whether a tub holds you comfortably, and these are the same measurements that guide uses.

Reading a Spec Sheet When You Cannot Measure the Tub

When the tub is not in front of you, the seat-to-overflow column on the spec sheet or drawing stands in for the tape measure. The published figures below are the ones to compare with your seated torso length. Where the sources give no companion figure, the cell says not listed.

The spread matters more than any one row. Across the mid-size seated models the figure runs roughly 15 to 18 inches, the Deluxe and the Big4One sit noticeably deeper, and the LayDown reaches a depth in the same range by a different route, since you recline on its floor instead of sitting on a seat. A seated torso measurement that lands near a model's figure means the water will come up to about your shoulders; one that runs well past it means a shallower, chest-level soak in that tub.

Sending Your Measurements for a Fit Check

If the depth you measure at home does not match the spec, or you want the team to confirm fit before you order, send your model, your seated measurements and a photo of the overflow with a tape measure standing from the seat, or from the floor on a LayDown, through ellasbubbles.com/support, or call your Ella dealer or the team at (800) 480-6850. Soaking depth is one of the directions a tub has to fit; the length, width and height of the alcove are the others, and how to measure your bathtub and alcove for a replacement covers those so the two sets of numbers travel together.

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

Related Guides

• Seat sizes and soaking depth: how to measure yourself for a comfortable fit
• Interior Length, Seat-to-Overflow and Seat-to-Footwell by Model: The Soaking Depth Table

Common Questions