How to size a bathtub
Measure the cutout, not the existing unit
Standard alcove tub: 60″×30″×14–17″ deep. The framing rough-in must match this within 1/8″. Drain location matters — pick a left- or right-hand drain to match the existing plumbing or be prepared to re-plumb. Freestanding tubs need 4–6″ clearance on visible sides.
Plumbing and electrical reduce usable depth
Supply lines, drains, vent ducts, and electrical run in the back 3–4″ of most cabinets. The catalog dimension assumes those connections sit flush against the back wall. If a previous installation routed lines along the side, the new unit may not fit even though the cutout looks correct. Pull the existing unit before ordering to confirm.
Standard vs. compact sizing
Compact / Japanese soaking: 48–54″ long, 28–30″ wide, 22–27″ deep. Standard alcove: 60″×30–32″. Freestanding: 60–72″ long, 30–36″ wide.
Common mistakes
- Assuming all "standard" units in the same category are interchangeable. Cabinet height varies by 1–2″ between brands.
- Adding new flooring under the existing unit; the new layer traps the unit under the counter.
- Ignoring door swing or pull-out clearance in front of the unit.
- Mixing US and EU standards. EU appliances are sized in centimetres (60 cm ≈ 23.6″), not 24″.