When I first dipped my toes—well, fins—into the world of scuba diving, one of the biggest questions floating around in my mind was: “How long does a scuba tank last underwater?” As a beginner, understanding the lifespan of a tank wasn’t just about curiosity—it was about safety, planning, and confidence. After all, the last thing any new diver wants is to be 40 feet down and worried about running out of air.

So, how long does a scuba tank last? The honest answer is: it depends.

Let’s break it down. The most common scuba tank used by recreational divers is an aluminum 80-cubic-foot tank (often referred to as an AL80). This tank holds about 3,000 psi (pounds per square inch) of compressed air. That sounds like a lot, but how fast you use it depends on several factors—your depth, your breathing rate, and even your body size.

As a general guideline, most beginner divers can expect a standard tank to last anywhere between 30 to 60 minutes underwater. But here’s the catch: the deeper you go, the faster you consume air. At 33 feet (10 meters), the pressure doubles, and so does the rate at which you breathe your tank dry. That means your tank could last half as long at 33 feet as it would on the surface.

In my early dives, I averaged about 40 minutes on a tank at a depth of around 40 feet. My dive buddy, who was taller and more muscular (and perhaps a bit more anxious), burned through his in just 25 minutes. That’s when I realized how personal air consumption can be.

There’s even a term for it—SAC rate (Surface Air Consumption rate). As you get more experienced, you learn to track and improve this. Relaxing, moving slowly, and mastering buoyancy all help stretch your tank time. I remember one instructor saying, “The best divers don’t swim—they glide.” That stuck with me, and sure enough, as I got more comfortable in the water, my air lasted longer.

Another factor to consider is the type of tank and air mix. Some divers use larger tanks (like 100-cubic-foot steel tanks) or enriched air (Nitrox) for longer bottom times. But as a beginner, you’ll likely start with standard air and basic equipment—which is totally fine. Focus on the fundamentals first.

So, to recap: a typical scuba tank lasts 30–60 minutes depending on depth, experience, and breathing rate. You can’t control the laws of physics, but you can definitely control how you dive.

My advice to fellow beginners? Don’t stress about the numbers too much. Dive within your training limits, check your gauges often, and always dive with a buddy. With each dive, you’ll learn more, breathe better, and stay down longer.