Bathtub Replacement Calculator
Calculates bathtub replacement dimensions across standard 60" × 30" or 60" × 32" standard alcove tubs, freestanding acrylic soaking tubs, 3-piece direct-to-stud surround wall panels, and left/right drain rough-in positions.
Formula
Tub Opening = 60" Stud-to-Stud; Wall Surround Area = (2 × Width + Length) × Height (~60 sq ft)
1. Standard Stud-to-Stud Pocket = Exactly 60.0 to 60.25 inches 2. Drain Rough-In = 8.5" to 9.0" from end wall and 14.5" to 15.0" from back wall 3. Surround Wall Area = (2 × 30 in + 60 in) ÷ 12 × 6.0 ft high = 60.0 sq ft 4. Mortar Bed for Base (50 lb bag sand-mix) = 2 bags under tub bottom for solid feel
Inputs
- Bathtub Format
- Tub Surround Walls
Worked example
Replacing a cast iron bathtub with an acrylic 60x30 tub and direct-to-stud surround.
Outcome: Requires 60" alcove tub (Left or Right drain hand), 3-piece acrylic surround kit, new brass cable-drive waste & overflow drain kit, and 2 bags of mortar for bedding under the tub basin.
How do you know if a bathtub is left-hand or right-hand drain?
Stand outside the bathtub looking directly into the open alcove. If the drain hole and faucet plumbing are on your left side, it is a Left-Hand tub. If they are on your right, it is a Right-Hand tub.