Minimum Gas Calculator

This calculator determines the minimum gas pressure needed to safely ascend from your maximum depth to your next gas source (usually air at the surface or a deco gas at a shallower depth) Together with your dive buddy.

• Max depth: The deepest point of your dive in meters
• Next air depth: The depth where you can access your next gas source (0 for surface air)
• Cylinder size: The volume of your cylinder in liters
• Extra time: Additional buffer time in minutes for safety
• SCR 1 & SCR 2: Surface consumption rates for each diver in liters per minute

The calculator computes the average depth pressure, total consumption rate, time needed to reach the next gas source, and the minimum gas required (rounded up to the next 10 bar).

If you don't know your SAC rate, you can use the SAC rate calculator to estimate it.

Usable Gas Calculator

This calculator determines how much gas you can actually use during the dive and at what pressure you should turn around.

• Rule: Choose how much of the usable gas you want to reserve:
  • All available: Use all usable gas (minimum gas is your only reserve). This can be used if you can safely ascend anywhere.
  • Half available: Reserve at half of usable gas (recommended for most dives). This should be used if it's safer to ascend at the same place you started your dive.
  • Third available: Reserve at two-thirds of usable gas (more conservative). This should be used if it's not possible to ascend at the furthest point of your dive and you have to be able to reach the entry point of the dive.
• Fill pressure: The pressure your cylinder was filled to in bar

The turn pressure is calculated as: usable gas minus the reserved portion, plus minimum gas. This ensures you always have enough gas to safely complete your ascent.