Standard bathtub size

Bathtub sizes chart

Tubs come in a few stock lengths: 48, 54, 60, 66 and 72 in. Here are 13 baths from Kohler's spec sheets. Length runs end to end, width from the back wall to the front, height from the floor to the rim. Water depth and capacity are Kohler's figures for each bath.

Alcove and drop-in tubs

Freestanding and corner tubs

Weights are the empty bath. Kohler spec sheets: K-1490-X, K-745, K-716, K-505, K-1123-LA, K-20202-LA, K-1229, K-1125-LA, K-5701, K-24011, K-6368, K-1155-F, K-1160. "Not listed": the current sheet gives the height only on its drawing.

Half of the alcove and drop-in tubs are 60 in long, and every one of those is 30¼ or 32 in wide. That is the size to plan for when a bathroom has a 5 ft alcove. Freestanding tubs measure larger outside for the same amount of water, and corner tubs are square.

Bathtub dimensions: length, width and height

An alcove tub has walls on three sides and a finished apron on the open side, so its length has to match the space between the end walls.

How long is a bathtub?

60 in (152 cm) is the standard length, the size that fits a 5 ft alcove. Kohler also lists 54 in (137 cm) for tight bathrooms, 66 in (168 cm) and 72 in (183 cm) for longer soaking tubs, and a 48 in (122 cm) Greek soaker that is deep rather than long (K-745, K-1229, K-1125-LA and K-1490-X spec sheets).

How wide is a bathtub?

30 or 32 in (76 or 81 cm). Both are standard: Kohler's cast iron Villager is 30¼ in wide and its Mendota 32 in, and the acrylic Archer and Underscore alcove tubs are 32 in. Kohler's 72 in Archer is 36 in (91 cm) wide. A 32 in tub gives a little more room at the shoulders; a 30 in tub leaves 2 in more floor in front of it.

How tall is a bathtub?

From the floor to the rim, the tubs in the chart run from 14 in (36 cm) for the cast iron Villager to 20¼ in (51 cm) for the acrylic Underscore. A taller tub holds deeper water, but you step over a higher rim. Kohler gives the Archer and the Underscore a 19 in (48 cm) step-over and a slotted overflow, and says they keep the water depth of a standard 21 in bath (K-1123-LA and K-20202-LA spec sheets).

How deep is a bathtub, and how many gallons does it hold?

Water depth is how deep the water can get before it reaches the overflow, and it varies far more than the outside size. Two 60 in tubs can differ by almost 7 in of water: 8 5/8 in (22 cm) in the cast iron Villager and 15½ in (39 cm) in the acrylic Underscore.

• Standard 60 in cast iron tub: 33 to 45 gal (125 to 170 L), with 8 5/8 to 10 7/8 in of water.
• 60 in acrylic soaking tub: 58 to 68 gal (220 to 257 L), with 15 to 15½ in of water.
• 72 in tub or freestanding soaker: about 60 to 73 gal (227 to 276 L).
• Corner tub: 76 gal (288 L) for a 54 in square, 96 gal (363 L) for a 60 in square.

Kohler's sheets add that the hot water supply should be at least 70% of the bath's capacity. For the 33 gal Villager that is about 23 gal (87 L) of hot water; for a 68 gal soaker, about 48 gal (182 L). Check the water heater before choosing a deep tub (Kohler K-24011 spec sheet, installation notes).

How much does a bathtub weigh?

Empty, a cast iron alcove tub weighs about 280 to 350 lb (127 to 159 kg): 277 lb for the 54 in Seaforth, 316 lb for the Villager and 351 lb for the Mendota. Acrylic tubs weigh 51 to 156 lb (23 to 71 kg). Plan for at least two people to carry a cast iron tub in, and check the route up the stairs.

Full, the water outweighs the tub. Water weighs about 8.34 lb per gallon (USGS conversion factors), so the 72 gal Archer holds about 600 lb (272 kg) of water on top of its own 80 lb, before anyone gets in. Kohler gives a minimum floor load for each bath, from 35 lb per sq ft for the 54 in corner tub to 61 lb per sq ft for the deep 48 in Greek. The code's floor joist tables are sized for a live load of 40 lb per sq ft in living areas (IRC Table R502.3.1(2), in Seattle's copy of the 2021 code), less than the higher figures, so ask a builder or engineer before setting a deep or cast iron tub on an upper floor. Our floor joist spacing guide covers how floors are framed.

Types of bathtubs

Alcove tubs sit between three walls, with a finished apron on the open side and a flange that runs up behind the wall finish. They are the standard 60 in tub and the usual tub-shower combination. Kohler names the drain end in the model: LA is a left-hand drain and RA a right-hand drain, seen standing in front of the tub (the K-1123-LA is "60 × 32 in alcove bath, left drain").

Drop-in tubs have no apron. They drop into a framed deck that you finish in tile or stone, so the deck adds a few inches all round. Kohler's Mariposa is 66 × 35 7/8 in on its own.

Freestanding tubs stand away from the walls on a finished floor, with the faucet on the wall, the floor or the tub deck. They tend to be longer and wider than the water inside them: Kohler's Sunstruck is 65½ × 35½ in outside.

Corner tubs fill a square corner, 54 × 54 or 60 × 60 in. They hold the most water of any tub here, so they need the most hot water.

Small and soaking tubs trade length for depth. Kohler's 48 × 32 in Greek holds 68 gal (257 L) with almost 18 in of water, as much as a 60 in soaker, but you sit upright in it.

How much space a bathtub needs

The International Residential Code sets clear spaces in front of toilets, sinks and showers, but not in front of a tub. North Carolina's code office, reading Figure R307.1, put it plainly in 2026: the bathtub has no clearance assigned, while a water closet and lavatory need 21 in (53 cm) and a shower 24 in (61 cm) (NC Office of State Fire Marshal). NKBA's guidelines do quote 21 in in front of a tub as the code figure, so ask your inspector which reading they use.

The recommendations go further. The National Kitchen and Bath Association recommends at least 30 in (76 cm) of clear floor from the front of every fixture, the tub included, to the nearest wall or fixture opposite (NKBA Bath Planning Guidelines, Guideline 4). For an accessible tub, the ADA Standards want a clear space at least 30 in wide along the full length of the tub, extended 12 in (30.5 cm) past the head-end wall when the tub has a permanent seat (ADA 607.2).

Two code rules apply when the tub has a shower head. The ceiling must be at least 80 in (203 cm) high over a 30 × 30 in (76 × 76 cm) area at the shower head, and the walls above the tub must be finished in a waterproof material to at least 72 in (183 cm) above the floor (IRC R305.1 and R307.2, as quoted in the NKBA guidelines, Guidelines 3 and 13).

So a standard tub takes a floor area of 60 × 30 in, plus 30 in in front of it: a 5 ft wide alcove about 5 ft deep to the opposite wall or fixture. The toilet beside it needs its own space; see toilet dimensions for the 15 in and 21 in rules.

How to measure for a new bathtub

Measure the space, not the old tub's label.

1. Length. For an alcove, measure wall to wall at the back of the tub, the front and the middle, at the height of the rim. Use the smallest figure. A 60 in tub needs about 60 in.
2. Width. Measure from the back wall to the front of the apron. Most replacements are 30 or 32 in.
3. Height. Measure from the floor to the rim. A taller tub raises the step-over and changes where the wall tile meets the tub.
4. Drain side. Stand facing the tub. If the drain is on your left, you need a left-hand drain (LA in Kohler's model numbers).
5. The way in. Measure doors, halls and stair turns. A 60 × 30 in tub has to get through them on its side.
6. Hot water. Read the capacity on the spec sheet and take 70%. That is the hot water the heater has to supply.

Questions people ask