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Scuba Tank Sizes: Everything You Need to Know to Choose Yours

Every underwater explorer must know their adventure companion: the scuba diving tank. They are also known as the provider of air beneath the ocean. It is vital.

For that reason, knowing the scuba tank sizes, pressure measurements, the materials they are made of, etc., is the only way to choose the best one for you at any given moment.

When you find yourself in this situation and have to choose the size of your scuba tank, you have to consider factors such as the weight of the cylinder, your gas consumption rate, the planned dive profile, and the air needs you will have, your comfort, and how much gas your buddy might need in case of an emergency.

This is why we wrote this article in which you will find the following information about the size of scuba diving tanks, pressure measurements, and much more.

1. Scuba Tank Definition

What is a diving cylinder?

Diving cylinders are those things that many non-divers call “oxygen canisters” and it gives scuba divers the creeps when we hear that name. These cylindrical tanks contain the air mixture that keeps us alive underwater, whether it’s regular compressed air, Nitrox, Trimix, or Heliox—all are pressurized into these cylinders. Of course, there are diving cylinders of various sizes. Let’s get to know them!


2. Scuba Tank Sizes and Pressures

2.1. Measurement Units of Scuba Tanks

It is important to note that the size of scuba diving cylinders is not as crucial in itself as their volume.

In Europe and South America, the volume of diving cylinders is measured in liters, while in the United States and Anglo-Saxon countries, it is measured in cubic feet.

The available volumes in the market range from small “pony” cylinders for emergencies, with capacities ranging from 6 to 40 cubic feet in North America and 1 to 4 liters in Europe, to the large main cylinders used by technical divers, reaching up to 150 cubic feet or 18 liters in Europe. However, determining if a scuba tank is full is not based on its capacity but rather on its pressure.


2.2. Scuba Tanks Working Pressures

Something similar happens with the pressures in scuba diving tanks. There are two measurements. For pressure, in North America, we use pounds per square inch or PSI, while in Europe, we refer to BARS.

No matter the scuba tank size, its working pressure is what will indicate its operability, and therefore, these measurements, although not directly related to the size of the scuba tanks, are crucial to consider their suitability for you.

There are high-pressure (HP) tanks with a capacity of 300 BARS/4,350 PSI and low-pressure tanks, and their size, both in inches and meters, will be directly related.

2.3. Scuba Tank Sizes Chart

We provide you with a chart displaying scuba tank sizes using U.S. measurement units so that you can observe the differences.

Capacity (Volume in Cu Ft) Length/Height (Inches) Diameter (Inches) Weight (When Empty in lbs)
3.0 13.4 2.25 2.2
6.0 11.1 3.20 2.5
19.0 17.7 4.38 7.8
40.0 14.6 5.25 15.3
77.5 25.9 7.25 31.3
80.0 20.9 7.24 28.6
98.8 26.2 8.00 41.1
105.0 26.1 7.40 33.8
120.0 29.1 7.25 39.2


2.4. Aluminum Vs. Steel Tanks: Material Differences of Scuba Tanks

Weight is another fundamental variable to take into account. Steel cylinders stand out for their robustness, allowing manufacturers to use less material compared to aluminum tanks of the same capacity, making them weigh less. Additionally, they tend to have greater negative buoyancy. Therefore, divers using steel cylinders need less lead for proper weighting.

Despite their negative buoyancy underwater, steel tanks have thinner walls than aluminum ones, often resulting in comparable or even lighter weight on land than equivalent aluminum cylinders. Despite their benefits, steel tanks pose some issues, such as the potential for corrosion and higher costs.

That’s why all tanks need maintenance and inspections. You can learn more about it in the article.

Scuba Tank Markings – Everything You Need To Know About Them

On the other hand, aluminum cylinders generally start with negative buoyancy but gradually shift to positive buoyancy as the diver consumes breathable gas. They also corrode much less, leading to a longer lifespan.

The 80-cubic-foot / 12-liter aluminum tanks are the most commonly used in recreational diving. These tanks, with lengths ranging from 21 to 26 inches, are particularly manageable for divers with less experience.

In this article, we have attempted to unravel the differences between scuba tank size, pressures, and materials to choose correctly. And you, do you have your own diving tank or do you rent one? Tell us on Facebook!