How-tos & Guides

A Guide to Standard Bathtub Sizes & Types

Read Time (
November 13, 2022
Kallista Design

The bathtub is often the most pivotal piece of a bathroom design. Depending on the dimensions and layout of your bathroom, you may find that a particular tub can give you the perfect balance of function and style.

From freestanding to drop-in or under-mount bathtubs, we’ll define and discuss standard bathtub sizes in this article, along with other important considerations.

Alcove Bathtubs

white alcove tub with mint green subway tiles installed vertically on the wall. showerhead, handles, and faucets in polished chrome

Standard bathtub sizes for alcove tubs are:

• Length: 4.5 to 6 feet
• Width: 2.5 to 3 feet
• Depth: 1 to 2 feet

While common in many households, an alcove bathroom can still be a striking fixture and help set the tone for your bathroom. An alcove bathtub is set against the far side, so the two long walls form the ends and back of the bathroom.

You’ll find that alcove bathtubs are ideal for smaller bathrooms about 6 feet wide. If the room is significantly larger than this, the walls may be too far apart to form an alcove. If you have a small bathroom, you may feel the need to forego a tub altogether and install a shower instead. This can give you additional functionality while still providing a spa-like atmosphere.

Drop-In & Under-Mount Tubs

top view of an undermount tub with chrome faucet and handle. soap and candles rest on the deck of the tub

Standard drop-in bathtub sizes in feet are:

• Length: 3.75 to 6 feet
• Width: 2.5 to 2.75 feet
• Depth: 1 to 2 feet

Drop-in tubs are designed to fit into a constructed deck with top and exposed sides completed with tile, stone, wood, or other materials. While not as common as alcove bathtubs, drop-in tubs are becoming increasingly popular because of the range of design options available. Under-mount tubs are similar, but instead of an exposed lip, they are fastened d to the bottom of the deck using heavy-duty clips and caulk.

In small bathroom designs, a drop-in tub can fit into the bathroom’s natural corner with only two sizes exposed. Still, the drop-in tub can be fitted into a pedestal deck for larger bathrooms, creating a centerpiece. Because a custom deck is required, drop-in bathtubs are best suited for medium to large bathrooms, especially considering that most designers advise at least a half foot of deck space around the tub.

When planning for a drop-in bathroom design, it's essential to remember that you’ll need to add at least a foot to both the width and the length to ensure that the custom deck will fit around the tub.

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Freestanding Bathtubs

white freestanding tub sitting in a partially outdoor bathroom with a window overlooking a bule sky

Freestanding standard bathtub sizes are typically:

• Length: 4.5 to 6 feet
• Width: 2 to 3 feet
• Height: 1.5 to 2 feet

Freestanding bathtubs tend to have a larger footprint because many people opt to have the area around the bathtub free of fixtures and set away from the wall.

Most designers suggest having at least three inches of space around the ends of a freestanding tub and a minimum of four inches between the sides and the walls. This means that you will need to add roughly 6 inches or a half foot to the tub measurements to ensure you get the full functionality of your tub and have a space that highlights your fixtures instead of making them look cluttered.

white claw-foot bathtub

Freestanding tubs are becoming increasingly popular because of the array of shapes, sizes, and designs that can give your bathroom a truly distinctive look. From vintage claw-foot tubs that bring a classic feel to oval deep soaking tubs perfect for pampering yourself, your design opportunities are nearly endless.

FAQs About Bathtub Sizes

What is the best bathtub size for small bathrooms?

The bathrooms in many homes, especially older homes, are designed to accommodate an alcove bathtub. This means that you should consider a bathtub that is 5 feet long, 2.5 feet wide, and 1.5 feet deep. This size can accommodate an average-sized adult while not making the space look cramped and cluttered.

What depth is best for a soaking tub?

The average bathtub size holds 42 gallons, but you will rarely fill the tub to its total capacity. Most soaking tubs are 15 inches deep, typically deep enough to cover most people. However, if you want to be almost entirely submerged, you can opt for a depth of 22 inches, which is the depth of many spa soaking tubs. It’s also important to consider the style of the tub. Cast iron tubs retain heat exceptionally well, making them ideal when you want a long soak to relax fully.

Is an oval or rectangular bathtub better?

That depends on what you envision your ideal bathroom to look like and the space you have to make your bathtub fully functional. There are some pros and cons for each style.

Round bathtubs carry more visual interest as they are less common than square tubs and have smaller footprints. However, an oval tub may require additional floor reinforcement. Additionally, an oval tub isn’t the most efficient use of space as it cannot sit flush with a corner of your bathroom.

Rectangular bathtubs are generally more affordable, and their versatile shape means they can easily be nestled into a corner of your bathroom or along its wall. You also get more deck space with a rectangular bathtub. However, rectangular bathtubs are more challenging to clean.

Discover the Perfect Bathtub Size

As the leading provider of luxury bathroom fixtures for over 40 years, KALLISTA carries a variety of bathtub sizes exquisitely designed and engineered for performance. Explore our luxury bathtubs online or at a showroom near you.

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