How Much Water Does A Bathtub Hold?
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When choosing the perfect tub, a main consideration is often how much water the bathtub holds. Of course, a bathtub’s primary purpose is to help you get clean. However, many people enjoy a long soak to relax or ease sore muscles, making the tub’s capacity essential.
Still, bathtubs come in all sorts of shapes, sizes, and styles, all of which affect how much water they hold. The average size of a standard tub is roughly 60 inches long, 30 to 32 inches wide, and 14 inches high. This size tub technically holds 70 gallons; however, the overflow drain would make it closer to 50 gallons.
The overflow drain is a safety measure to keep a bathtub from overflowing. But it can also limit how deep a soak you get since the water can’t surpass it. So, when determining a tub’s capacity, you should consider the overall size as well as the placement of the overflow drain.
Determining The Capacity Of A Bathtub
To easily figure out how much water a tub will hold, it’s a matter of some simple math. You can use the formula for capacity in gallons by multiplying the tub’s length, width, and height, then dividing by 231. For example, a 60-inch-long tub that’s 32 inches wide and 14 inches tall would have a capacity of roughly 116 gallons. The formula would look like this:
60 (length) x 32 (width) x 14 (height)=26,880 cubic inches/231=116.36 gallons
You Need To Use Interior Dimensions
But wait–not so fast. The next thing to keep in mind is using the interior dimensions of the tub. Most tubs give you the overall external dimensions from the floor to the top of the tub and edge to edge.
However, the interior space of the tub would typically be less than this to account for the tub’s structure. You would get about 1.5 to 2 inches less height and roughly 6 to 8 inches less in width. Additionally, the length would be about 4 to 6 inches less, all depending on the thickness of the tub.
Therefore, the altered formula would look more like this:
56 (length) x 24 (width) x 12 (height)=16,128 cubic inches/231=69.8 gallons
As you can see, that’s a big difference in capacity.
Consider The Overflow Drain
You also need to consider the overflow drain placement, which is behind the tub. Typically, you’ll see a metal overflow faceplate on the tub’s wall, held in place by one or two screws.
Toward the bottom of this cover, you’ll see a notch or opening where water goes to prevent overflowing. So, while you’re making the water as deep as possible for an ample soak, the overflow drain is working against you.
The overflow drain placement can vary but is usually about 2 or 3 inches from the top of the tub. Therefore, you would have more space between the overflow and tub bottom in soaking tubs.
So, if the bottom of the overflow cover is 8 inches from the bottom of the tub, the interior height changes to 8 inches. Now, your new formula would look like this:
56 (length) x 24 (width) x 8 (height)=10,752 cubic inches=46.55 gallons
Now, you’ve gone from 116 gallons based on external dimensions down to less than 50 gallons. But this illustrates why the actual height of a tub doesn’t dictate your available soaking room.
How Much Water Do Different Bathtubs Hold?
You can opt for an average-sized tub, oversized soaker, corner tub, oval tub, and more. This means you can also end up with many different shapes and sizes, all holding a different amount of water. Here is a look at some of the most common types of tubs and their average sizes.
1. The Size Of Alcove Bathtubs
Some of the most common bathtubs are alcove tubs that fit into an existing bathroom alcove formed by three walls. Many of these spaces are typically standard, but you can fit a smaller tub by building out one side of the wall.
Standard tubs can range in size from small to mid-sized. Plus, while many tubs are rectangular, you can also find oval-shaped alcove tubs.
Rectangular Alcove Tubs
Average rectangular alcove tubs are between 4.5 to 6 feet long and 30 to 36 inches wide. They have a height of 14 to 18 inches. When accounting for the tub’s structure and the overflow drain, this tub would hold between 41 and 98 gallons.
In new builds, many people choose to place longer soaking tubs in an alcove. These tubs can be closer to 20 inches tall, with an interior height of roughly 18 inches. You could hold about 130 gallons in this extra-deep tub.
Oval Alcove Tubs
Oval tubs, also called garden tubs, are typically designed for soaking. They are usually the same length as a standard tub, between 60 and 72 inches. However, they are wider (about 41 inches) and deeper (about 24 inches).
Therefore, a 60-inch oval tub could hold up to 161 gallons of water, and a 72-inch oval tub holds about 196 gallons.
2. The Size Of Drop-In Tubs
Drop-in tubs tend to hold more water than alcove tubs of similar size because they don’t include factory-finished sides. Drop-in tubs literally drop into a deck that usually features tile sides or some other finishing material.
Because of this, the tub’s interior dimensions are a bit closer to the exterior dimensions. Drop-in tubs can be between 45 and 72 inches long, 30 to 32 inches wide, and 14 to 20 inches tall. Because of the wide range of sizes, they can typically hold between 50 and 150 gallons.
3. The Size Of Corner Bathtubs
Corner bathtubs usually take up a square footprint that can measure 60 by 60 inches and roughly 22 inches tall. The interior of the tub is triangular, with a soaking depth between 18 and 20 inches. Depending on the size tub you get, a corner tub could hold about 95 to 115 gallons.
4. The Size Of Freestanding Tubs
You can find many unique styles of freestanding tubs, many of which are extra deep for the ultimate soak. Otherwise, the width and length are comparable to other tub styles.
Freestanding tubs can range from 55 to 72 inches long, 25 to 32 inches wide, and 15 to 22 inches tall. The height from the bottom of the tub to the overflow drain is usually about 13 to 15 inches.
Also, freestanding tubs usually don’t have as wide of a rim as tubs in an alcove. Therefore, most freestanding tubs will hold between 61 and 125 gallons of water.
5. Whirlpool Tubs
You might assume whirlpool tubs hold more water because they usually have slightly larger exterior dimensions. Some of them just appear larger. But typically, these additional inches only affect the tub’s structure.
This is because of the jet mechanisms and other components that are inside the walls of the tub. However, the tub’s interior would hold a similar amount of water to similarly-sized regular tubs.
Frequently Asked Questions
Is there a way to keep the water level higher in my tub?
If you’re getting frustrated with the water level dropping in your tub, you can do an easy and quick fix. You can buy an overflow cover that will block the hole in your overflow faceplate. This way, when the water level rises above the overflow plate, it won’t start to drain.
You can typically find these covers online and at home improvement or bath accessory stores for about $7 to $15. Just be aware that covering the hole diminishes any safeguards in place for water overtopping your tub. So don’t leave your tub unattended while you’re filling it, or you risk water going all over the floor.
How much water will a tiny tub hold?
With the increasing popularity of tiny houses and smaller spaces, extra-small tubs are making an appearance. If you have a small bathroom and don’t want to stick with a shower, a tiny tub could be your answer.
These smaller tubs can be closer to 51 to 54 inches long and 28 to 30 inches wide. The most significant difference is tiny tubs will typically be taller to accommodate for their smaller footprint. Therefore, you can find small tubs that are 23 to 29 inches tall.
On average, small tubs can hold between 68 and 120 gallons of water.