Who is a 48-inch bathtub for, and what room does it need?

Q: Who is a 48-inch bathtub for?

It suits a guest or secondary bath, a small room or apartment-scale bathroom, and a bather who prefers to sit and soak. Taller bathers will sit with knees bent. If you want to stretch out, step up to a longer size.

Q: How many gallons does a 48-inch tub hold?

A 48 × 27.5 in freestanding soaker is listed at 47 gallons. Our model gives 45 gallons for a stone oval of 48 × 28 × 22 in filled to 70% of the basin. An alcove 48 × 32 in tub with 12-1/2 in of water holds less.

Q: How much clearance does a 48-inch tub need?

At least 21 in of clear floor in front of the tub under the IRC. A freestanding one also wants about 4–6 in behind and beside it for cleaning, so the footprint to plan is roughly 56–60 in by 36–40 in, plus the front clearance.

Q: How much does a 48-inch stone tub weigh filled?

A solid marble oval of 48 × 28 × 22 in weighs about 820 lb empty and about 1,400 lb with water and a 200 lb bather, which is 190 psf on its footprint. Travertine is lighter at about 760 lb empty. A structural check is needed in both cases.

Last updated November 2026.

Quick answer

Footprint: 48 × 27.5 to 32 in on maker sheets, about 9–10.7 sq ft
Water: 47 gal for a 48 × 27.5 in freestanding soaker (maker); 45 gal at 70% fill for a 48 × 28 × 22 in stone oval (our model)
Clear floor in front: 21 in under the IRC; see the clearances guide
Hot water: About 35 gal from the tank for a 45 gal bath
Solid marble, 48 × 28 × 22 in: About 820 lb empty, about 1,400 lb filled with a bather, 190 psf

A 48-inch bathtub is the shortest common size, suited to guest baths, powder rooms with a tub and tight primary baths where a 60-inch tub will not fit. It holds roughly 45–47 gallons in freestanding form, takes about 9 sq ft of floor, and needs 21 in of clear floor in front.

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Who is a 48-inch bathtub for?

It is the tub for rooms where every inch is spoken for. This Old House places 48–54 in lengths in the compact class, for small bathrooms, apartments and guest suites. Think of a hall bath with an 8 ft wall, a basement bathroom, or a primary bath where a shower and a window leave only a short wall free.

It is also the sensible pick for a bather who soaks rather than stretches out. Because a 48 in tub is an outer measure, the inside length is closer to 43 in once the walls are subtracted, so the posture is seated with knees bent. For a ready comparison of every length, see the bathtub sizes guide.

Planning a stone bathtub?

Tell us about the room. We reply within one business day with options, and every quote gives the exact dimensions and weight of the piece.

How much clearance does a 48-inch tub need?

The tub itself covers about 9.3 sq ft at 48 × 28 in, against 12.5 sq ft for a 60 × 30 in tub. The room around it is what changes the plan. Drench, a freestanding-bath retailer, puts the minimum gap from a wall at 10–15 cm (about 4–6 in) for airflow and cleaning. Add that to both sides and both ends of a 48 × 28 in tub and the footprint to reserve is roughly 56–60 in by 36–40 in.

In front, the IRC asks for 21 in of clear floor at a tub, and design guides recommend more. This Old House suggests 30 in. Door swing, the toilet's 15 in side clearance and a vanity all compete for the same floor, so draw the room to scale. The numbers and the reasoning are in the bathroom clearances guide.

Alcove or freestanding at 48 inches?

Both exist, and they behave differently. An alcove tub slides between three walls and shares them as supports and splash guards. A freestanding tub stands alone and needs the gap on all sides, but its walls can be taller, which matters because depth does the work that length cannot.

Example	Outside size	Soaking depth	Capacity	Weight
Voltaire SM-AB552BQ, three-wall alcove, acrylic	48 × 32 × 21-5/8 in	12-1/2 in	Not listed	62 lb
Cube freestanding soaker, acrylic	48 × 27.5 × 26 in	22.9 in	47 gal	88 lb
Stone oval, our model, 70% fill	48 × 28 × 22 in	About 13 in of water	45 gal	820 lb empty

Sources: Voltaire spec sheet; retailer listing for the Cube; Pietra Fonte weight model. About 13 in is our estimate: 22 in height less the 3 in base, filled to 70%.

The alcove version is shallow at 12-1/2 in of water, so a bath is more of a wash than a soak. The 26 in freestanding soaker holds nearly twice the water depth in a smaller footprint. For plumbing positions in either case, see the drain rough-in guide.

How many gallons does a 48-inch tub hold?

It depends on the water depth, not the length. At 44 × 24 in inside, which is close to a 48 × 28 in stone oval, our gallons calculator returns these figures. Rectangular tubs with square corners hold about 15% more than ovals.

Water depth	Oval	Rectangular	Water weight, oval
14 in	50 gal	58 gal	About 417 lb
16 in	57 gal	66 gal	About 475 lb
20 in	72 gal	82 gal	About 600 lb

Source: Pietra Fonte gallons calculator. Use the calculator for your own inside size.

The 45-gallon figure in the facts above is lower because our weight model stops at 70% of the carved basin to leave room for a bather. Maker figures such as the Cube's 47 gallons follow each seller's own fill rule, so compare them with care.

What water heater does a 48-inch tub need?

Less than most. A 45-gallon bath at 104°F needs about 35 gallons from a 120°F tank, using the 77% mix from our hot-water model. Kohler's spec sheets say the hot water supply should be 70% of the bath's capacity or more. A standard 40–50 gallon tank with a good recovery rate can usually manage one bath, which is a real advantage over a 72 in tub.

Confirm with a licensed plumber, who can read the heater's first-hour rating against what else runs in the house.

Is a 48-inch tub long enough to bathe in?

For a seated soak, yes. For lying back, no. With 2.5 in stone walls, a 48 in outside length leaves about 43 in inside, so an adult sits with knees raised. A deep freestanding shape helps because water covers the shoulders even when the legs are bent.

If two people share the bath, or the bather is tall, a 54 or 60 in length is the next step. The bathtub sizes guide lays the lengths side by side.

How much does a 48-inch stone tub weigh filled?

More than its size suggests. Our weight model gives 820 lb empty for marble and 760 lb for travertine at 48 × 28 × 22 in. With 45 gallons of water (370 lb) and a 200 lb bather, a marble tub reaches about 1,400 lb. That is 190 psf on a 9.3 sq ft footprint, the highest figure in our size range, because a short tub spreads its load over less floor.

Compare acrylic: the Voltaire sheet lists 62 lb and the Cube listing 88 lb. A 40 psf design floor will not carry stone without checking the framing. See the stone bathtub weight guide. Pietra Fonte quotes are made to order, so each quote states the exact size and weight. For what stone tubs cost in the market, see the marble bathtub cost guide.

Sources

Every piece is made to order. Tell us about the room and we reply within one business day.

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