Rock Bottom Calculator

Rock Bottom — Key Features

• Calculate minimum gas for emergency ascent from any depth
• Configurable stress factors (2×, 2.5×, 3× SAC)
• Account for buddy air sharing during emergency
• Include safety stop gas consumption
• Get your recommended turn pressure
• Support for custom ascent rates and stop profiles

Rock Bottom — How It Works

Enter your maximum depth, tank size, SAC rate, and stress factor. The calculator computes the total gas needed for an emergency ascent — including stressed breathing, buddy sharing, ascent time, and safety stop. It then converts this to a turn pressure, telling you when to start heading back.

Why Calculate Rock Bottom?

• Never run low on gas in an emergency situation
• Know exactly when to turn your dive around
• Account for worst-case stress and buddy sharing
• Essential safety practice for all divers

Rock Bottom — Frequently Asked Questions

What is rock bottom?

Rock bottom is the minimum gas reserve you need to safely ascend from your maximum depth in an emergency. It accounts for increased breathing under stress, sharing gas with a buddy, and completing a safety stop.

What stress factor should I use?

The stress factor multiplies your normal SAC rate. Use 2× for moderate conditions, 2.5× for more challenging dives, and 3× for high-stress scenarios like deep or overhead environments.

Should I include buddy sharing?

Yes, unless you dive solo. Rock bottom should account for sharing gas with a buddy who has run out of air, as this doubles the gas consumption during the emergency ascent.

How is rock bottom calculated?

The calculator adds up gas needed for each phase: swimming at maximum depth to the ascent point, ascending at a safe rate (typically 9 m/min), performing a safety stop, and reaching the surface. Each phase uses your SAC rate multiplied by the stress factor.

Does rock bottom change with depth?

Yes, significantly. Gas consumption increases proportionally with ambient pressure. A diver consuming 20 L/min at the surface uses 60 L/min at 30 meters (4 bar). Deeper dives require substantially more reserve gas, making rock bottom calculation critical.

Should I include a safety stop in my rock bottom?

For recreational dives, including a 3-minute safety stop at 5 meters is recommended even in emergencies. For decompression dives, all mandatory stops must be included in your rock bottom — skipping them creates a serious decompression sickness risk.