How Long Does A Scuba Tank Last?


A scuba tank lasts from 10 minutes to about an hour. If the conditions are perfect and your fitness level combined with your breathing technique is well developed, it may reach even the 90-minute mark. The real questions are – how, why, when, and what? How can the time vary, why the difference is so big, when does it last longer, and what to do to make sure you don’t lose the oxygen while deep under the surface?

Many factors affect the usage of the air from a scuba tank, and in this article, we’ll be through those factors, how can they alter your dive, and we’ll also go through situations that may force you to get out of the water before you reach the end of your air supply.

Five Contributing Factors

OK, we know in theory – a scuba tank will most often last between 10 minutes and an hour, with the possibility of going up to 90 minutes. Which one will depend on these six factors – depth, tank capacity, tank pressure, lung capacity, overall body fitness, and breathing rate. Let’s check them out each one individually:


Remember how, when the weather forecast says that the atmospheric pressure is high, it is a bit harder to breathe than when it is normal? It is because that pressure makes the air denser. The normal atmospheric pressure is 1 bar/ATA. When you enter the water and as you dive it increases with the 1 bar/ATA per 33 feet (10 meters) rate. This means that the rate will be 2 bar/ATA at 33 feet mark because of the 1 bar/ATA water pressure), and as you dive deeper, it will increase by 1 bar/ATA every 33 feet.

Atmosphere pressure directly affects the air volume. Basically, the bigger the pressure is, the denser the air will be. Let’s place it in our known environment. The pressure won’t affect the amount of air but the amount you inhale. As the density increases, you’ll have to take more air with each breath to breathe properly. This means you’ll have to inhale more often, or bigger breaths. With this, it is not hard to learn whether your air tank will be enough. Just check your diving plan, see the diving depth and you’ll know approximately how much air you’ll use.

Simply said – the deeper you go, the more air you’ll need, and the quicker your container will empty. The same one may last more than an hour if you’re somewhere near the surface, but it could also drop to just 10 minutes if you go deep enough.

Tank Capacity – how much air is in a scuba tank?

The other important question is how much air is in a scuba tank? And the answer is – about 80 cubic feet of compressed air at 3000 psi (pounds per square inch), which is about 6.5 pounds heavy. But this could also wary. Most often scuba diving tanks are marked as 12-liter tanks (although it is a bit smaller, it is simpler to round the number). There are also 8-liter, 10-litre, 15-litre, and 18-liter tanks. The logic is simple – the bigger the tank is, the more capacity it will have, thus last longer. Of course, the bigger doesn’t always mean the better. Take your own size, strength, and condition into consideration when choosing the right one because the air also has some weight. Do not overestimate yourself or you’ll end up with a problem to deal with under the surface. That is why it is recommended to test it out somewhere in the controlled environment before you take it to the water. Also, if you’re a beginner, you’d probably be good with the smallest one, until you reach the level needed to go to the bigger depths.

Tank Pressure

Most often tanks are filled at 200 bar / 3000 psi. To learn how much your tank can hold, check the stamp placed on the neck. The math here is simple – the more pressure, the longer you’ll be able to be under the surface. But, you’ll also have to know your no-compression limit, because you may reach the no-stop limit with less than half of your tank.

Lung Capacity


This one is strictly individual. You don’t have the same lung capacity as your friends or as most of the other divers. This affects air consumption in two ways –the size and the breathing technique.

  • The size matter is the saying, and it is quite true when it comes to scuba diving. The bigger you are, your chests will most likely follow, which means your lungs depend on your size. There are also factors regarding the way of life – for instance, if you’re a smoker, you’ll probably have smaller lung capacity compared to someone who is the same size as you, but works out regularly, etc. If two people of different sizes have the same breathing rate, most likely the bigger one will empty the tank faster. The reason is simple – the larger the lungs, the more air they’ll need.
  • The proper breathing technique will help you get the most out of each breath you take, so you won’t have to take it too fast. This way your tank will stay filled for a longer period of time.

Overall Fitness Level

The logic is easy to understand – when in a good shape, breathing is done easier and without a problem. Your muscles are more relaxed and it doesn’t take as much effort to breathe properly and regularly. This is why it is recommended to start a swimming workout. This way you’ll be prepared for your diving session and ready to descend.

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Breathing Rate

As mentioned above, proper breathing techniques will help you not only get the best out of each breath you take, but you’ll also use less air. The key is to breathe deep and exhale slowly. You’ll achieve this by exhaling long and steadily so all the carbon dioxide leaves your lungs. Carbon dioxide is most often the substance that forces you to breathe irregularly. This is the waste gas so your body is trying to get it out of your system. When it reaches the critical level, you get the urge to breathe to remove it.

By taking more time to exhale, you’ll remove it from your body and you won’t have to breathe as fast as you would in general. And deep breathing improves a scuba diver’s health along the way.

Globo Surf Overview

To answer a question of how long does a scuba tank lasts is not enough to say precisely – 10 minutes, an hour, or two hours. Many factors could affect this. We hope this article has helped you understand this matter a bit better, so the next time you go to buy a scuba diving tank you know what to look for, based on your previous experience. By learning them, you’ll be sure to know what to do to stay safe while scuba diving.

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