How much weight do I need? How will tank X influence my buoyancy? Is tank X good for sidemount diving?
With this calculator, you can either view the characteristics of pre-defined tanks or enter data for a particular tank you are interested in. The calculator will then tell you the tank’s buoyancy when full and when empty in kg.
Some of these values may seem counterintuitive at first. Please remember that aluminum tanks need much thicker walls due to their lower strength compared to steel, which makes them heavier than steel tanks out of the water and more buoyant in the water due to their much thicker walls compared to steel tanks.
Below are example calculations for some tanks commonly used by technical divers.
| Tank type | Aluminum 80 cu ft | Faber light steel old | Faber light steel new | ECS cylinder concave |
|---|---|---|---|---|
| Tank characteristics | Aluminum 11.1 l 200 bar 14.4 kg | Steel 12 l 200 bar 12 kg | Steel 12 l 200 bar 11.5 kg | Steel 12 l 232 bar 14.6 kg |
| Gas volume | 2220 l | 2400 l | 2400 l | 2784 l |
| Freshwater | ||||
| Buoyancy full / empty | -1.4 / 1.3 kg | -2.1 / 0.8 kg | -1.7 / 1.3 kg | -4.9 / -1.5 kg |
| Buoyancy at 50 bar | 0.6 kg | 0 kg | 0.6 kg | -2.3 kg |
| Average buoyancy | -0.05 kg | -0.65 kg | -0.2 kg | -3.2 kg |
| Saltwater | ||||
| Buoyancy full / empty | -1.0 / 1.7 kg | -1.8 / 1.1 kg | -1.4 / 1.6 kg | -4.5 / -1.1 kg |
| Buoyancy at 50 bar | 1.0 kg | 0.4 kg | 0.9 kg | -1.8 kg |
| Average buoyancy | 0.35 kg | -0.35 kg | 0.1 kg | -2.8 kg |
