The question “how long does a scuba tank last” nearly always relates to diver air time while underwater. But it’s sometimes asked with the life of the tank itself in mind.\nConcerning the latter concept, the expectancy of a tank in terms of physical lastness is around 30 years (yes, seriously). But if your primary concern is knowing how much time the air inside will accommodate you underwater and how you can increase that timespan, I’m here to help you figure that out. You’ll go cool-minded and confidently onto your dives from now on!\nHow Long Does Scuba Tank Last Underwater?\nThe straight answer is: The higher the air volume a tank holds, the longer it’ll last underwater. But there’s more than a mere air volume. The tank’s longevity highly depends on the level of the diver’s physical exertion and the depth at which it’s used. On average, an open-water certified diver using a standard aluminum 80-cubic-feet tank on a 40-foot dive can stay down for about 45 minutes before surfacing with a safe air reserve.\nFew Factors That Determine the Longevity of A Diver’s Air Tank\nTank Volume\nIt’s as apparent as it seems - the higher the internal volume of the tank, the longer it’ll last. This is because deeper or longer dives require a greater internal air volume and vice versa.\nThe most common tank is an aluminum 80-cubic-foot that holds 80 cubic feet of air compressed to 3000 pounds per square inch (PSI). However, they can come in different materials and sizes, each used for varying applications. Concerning the tank's durability, we recommend opting for aluminum material tanks as rust is the biggest problem with steel-made tanks.\nAir Consumption Rate\nHow much air a diver consumes directly impacts the air longevity of the tank. The diver’s Surface Air Consumption (SAC) rate will determine how much air the diver is likely to consume. Also, figuring out how long a tank lasts on the surface will answer how long it’ll last underwater.\nDivers with large lung volumes (tall or large bodies) will require more air than those with smaller ones (petite or short). However, women often have smaller lung volumes, having an advantage in air-consumption rates when scuba diving. Congrats ladies!\nDepth\nThe more fathoms (measurement of water depth) a diver fills down there, the more quickly they’ll use up the air in the tank. This is because water is denser than air, increasing pressure around the underwater diver.\nLogically speaking, the underwater pressure doesn’t affect the air in the tank, but it does affect the air the diver releases passing through their regulator hoses.\nThe difference between the underwater air and the surface makes up half of it. For example, the amount of air that fills one cubic foot on the surface will fill only ½ a cubic underwater (at a depth of 33 feet). So if a diver consumes an 80-cubic-feet tank in 60 minutes on the surface, they’ll last for 25 minutes underwater with 20% reserve air in the tank on surfacing outside.\nTips to Make Your Tank Last Longer Down There\nThough Experience is one of the factors that matter greatly, there are some tips to improve your air consumption:\n\nRelaxed, slow, and deep breathing is usually the best way to reduce your air consumption rate.\nStay relaxed both mentally and physically. If something terrifying happens, just relax and find out what you can do to solve it.\nDon’t use your arms for swimming. This will help lower the level of your physical exertion.\nFind perfect buoyancy and kick efficiently, not constantly.\nMove slowly and as little as possible.\n\nFinal Thought\nSo that was a pretty clear idea of how long a scuba tank lasts. It’s a win-win situation - some factors affecting and determining the tanks' longevity depend on the tank itself, and some on you. As a final piece of advice, stay fit and healthy to help your cardio function work appropriately so as not to lose your breath during the diving and help you consume less air.