There are many factors that affect the time a tank will last you.
- First of all, the size of the tank. There are many sizes of tanks. A very common tank is the "Aluminum 80". This means it holds 80 cubic feet of air in a compressed state. This is 2265.35 litres of air.
- Secondly the size and air consumption of the person using the tank. A very large person will use more air than a very small person.
- This is also determined how relaxed you are. Someone very eager and excited or nervous to go diving will use more air than someone that is calm and relaxed.
- Thirdly, the depth you dive to. Every foot deeper that you dive increases the amount of air you use as the regulator needs to compensate for the added pressure of the water. A dive to 130 feet will use 5 times more air than a dive to 1-2 feet.
As a guestimate, an average person that is fairly experienced and relaxed that dives around 20-30 feet using an 80 cubic foot tank could make a tank last about 45 minutes to an hour.
