Six Measurements To Check Before You Buy A New Bathtub

There are two kinds of people in the world: those that include a big, luxurious soaking tub or whirlpool in their bathroom remodel because they feel like they have to, and those that do so because they really really want to. But whether you’re approaching the purchase of a big bathtub out of a sense of obligation or enthusiasm, there are a few important measures and markers that you should keep in mind, so you can be sure to get a bathtub that you’ll love to use – or, at the very least, that won’t work against you in terms of resale value later.

Length

Marie Louise Cast Iron Clawfoot Tub From Herbeau
Marie Louise Cast Iron Clawfoot Tub From Herbeau

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When you’re talking about upgrading to a luxury bathtub, you’re almost definitely talking about a boost in length. This may not be true 100% of the time, but it’s pretty darn close. The reason is that stretching out and sinking down into the tub is a key part of the luxury soaking experience. That said, unless you’re pretty tiny, even the longest tubs aren’t big enough for you to lie flat in them. So while a 72″ beauty can sound like a dream, if your space is limited, you can actually get away with sizing down a little, as long as the back of the bathtub has a comfortable slope to it, and a fairly generous overflow drain (more on that in a moment).

Height

Acclaim ADA Approved Bathtub With 15" Apron From Sterling
Acclaim ADA Approved Bathtub With 15″ Apron From Sterling

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Determining the total height of your bathtub is probably one of the simplest measurements that you should be aware of, and one that should be listed clearly on every bathtub. That said, it isn’t always the first measurement you think of: often the length of the tub is the biggest selling point, and a ballpark understanding of the capacity of the tub is often left to the figure in gallons, rather than the height. The inside height and outside height of a bathtub also doesn’t necessarily match, meaning that while the outside height is often the number listed, it isn’t always the best representation of how much room you’ll have to soak. Knowing the total height of the tub walls, then, is primarily an accessibility issue: the taller the tub, the more difficult it will be to get in and out of, especially as you grow older. For especially tall tubs, it can even be worth installing an extra step up to help you over the wall.

Depth

Midas Oval Freestanding Bathtub 34 x 71 x 18 VZ3471RS from Venzi
Midas Oval Freestanding Bathtub 34 x 71 x 18 VZ3471RS from Venzi

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Why don’t the inside height and outside height of the tub walls match? On a clawfoot tub or pedestal tub, the reason is obvious: the feet raise up the bathtub so the inside doesn’t even touch the floor. This is less evident in solid, rectangular bathtubs, but even in the simplest fiberglass tubs, there’s a few inches between the bottom of the tub and the floor, purely because of the way the tub is made. In a very large bathtub, a few inches might not make much difference, but the more shallow the tub, the less water it can hold, to the point that you may not even be able to cover your body with water with the bathtub filled all the way up to the overflow.

Overflow Drain

Villa 32 x 60 Rectangular Soaking Bathtub VZ3260VN from Venzi
Villa 32 x 60 Rectangular Soaking Bathtub VZ3260VN from Venzi

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While many of the measurements of a tub are fairly straightforward, the inside depth of the tub can actually be a little misleading. Why? Because only very rarely is it possible to fill a bathtub all the way up to the rim, as nearly all tubs are equipped with overflow protection that will steadily drain the water once it reaches a certain level. Knowing the height of this secondary drain is absolutely crucial, as it will mark how deep the water in your bathtub will actually be, regardless of the inside height of the tub.

Capacity

Aqui 48 x 73 Rectangular Soaking Bathtub VZ4878C from Venzi
Aqui 48 x 73 Rectangular Soaking Bathtub VZ4878C from Venzi

As with the fill height, the water capacity is another bathtub stat that can be a little misleading. Not only is it a little difficult to picture what 70 or 80 gallons of water might look like once it’s in the tub (and produce a different level of water depending on the length and width of the bathtub), but the capacity of your tub does not correlate one to one with the size of your water heater. You might think, 50 gallon tank, 50 gallon tub, but the result is, at best, a lukewarm bath because cold water will flow into the water heater to refill it, even as you’re draining the hot water for your tub.  Many retailers will neglect to mention this because replacing your water heater will take the whole project to an entirely different level, but if you want to ensure you can fill your tub with piping hot water, make sure your water heater can handle the increased demand.

Weight

Retro Cast Iron Charleston Clawfoot Soaking Tub From Herbeau
Retro Cast Iron Charleston Clawfoot Soaking Tub From Herbeau

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Last but certainly not least, if you’re planning on buying a new luxury soaking tub, you really want to know how much it weighs, specifically when it’s as full of water as it can get, and especially if the tub is made of cast iron. Why? Because water is heavy, and cast iron is heavy, and the two together can spell disaster if your floor isn’t  up to bearing their combined weight. This is mostly an issue for bathrooms on upper levels, but really anywhere the tub won’t be placed on a solid foundation, make sure to have a chat with your contractor about whether or not your floor can handle your dream tub.

Why are you in the market for a new bathtub? Are you a bath lover or are you upgrading with an eye to resell? Let me know in the comments!