Dive Gas Time Planner (Tank Duration Calculator)

How to Use This Dive Gas Time Planner

This tool estimates your approximate usable bottom time at a planned depth based on your gas consumption and cylinder setup. It is for educational planning only.

You will need:

  • Your planned average depth
  • Your RMV (Respiratory Minute Volume) in L/min (from the SAC/RMV calculator)
  • Your cylinder size (internal volume in litres)
  • Your starting pressure (bar)
  • Your reserve pressure (bar you want to keep in the tank)

Steps:

  1. Enter your planned average depth (not maximum depth)
  2. Enter your RMV at the surface
  3. Enter your cylinder size (e.g. 12 L steel, AL80 ≈ 11.1 L)
  4. Enter your starting pressure and your reserve pressure
  5. Choose a conservatism factor (recommended: Conservative)
  6. Click Calculate Gas Time

The calculator will show:

  • The gas consumption rate at depth
  • The usable gas volume
  • Your estimated bottom time in minutes

Always plan conservatively and follow your training, gas rules, and dive computer. This tool does not replace proper gas planning or professional instruction.

Dive Gas Time Planner (Tank Duration Calculator)

Estimate your usable bottom time at depth using your RMV, cylinder size, starting pressure, and a reserve. Educational planning only.

Safety note: This tool is for educational planning only and does not replace training, a dive computer, or gas planning procedures taught by your agency/instructor. Always plan conservatively.

Inputs

Use planned average depth (not max).
L/min
Tip: get this from your SAC/RMV calculator.
litres (L)
Example: 12L steel, 15L steel. (AL80 ≈ 11.1 L)
bar
bar
Set a conservative reserve (more in current/cold/stress).
Multiplies RMV to account for real-world conditions.

Quick FAQ

What RMV should I use?

Use your measured RMV from several relaxed dives. For planning, use your typical value or a conservative higher value.

Why do you use “average depth”?

Because gas consumption depends on pressure over time. Average depth gives a more realistic estimate than maximum depth.

Does this replace proper gas planning?

No. This is an educational estimator only. Follow your training, procedures, and always plan with reserves and safety margins.

Gas Planning Tips for Safer Dives

Your available gas time depends on much more than just cylinder size and depth. Keep these points in mind when planning any dive:

🧠 Use a realistic (or conservative) RMV

Your RMV increases in current, cold water, stress, poor visibility, or task-loaded dives. For planning, use your higher, real-world RMV, not your best-case number.

⏱️ Plan using average depth

Gas consumption depends on pressure over time. Using average depth gives a more realistic estimate than planning from maximum depth.

🛑 Always keep a reserve

Never plan to use your entire tank. Keep a generous reserve for ascent, safety stops, and unexpected situations — especially when diving deeper or in current.

🤝 Plan for your buddy

Your reserve should allow you to help a buddy in an emergency, not just get yourself to the surface.

❄️ Add margin in demanding conditions

Cold, current, low visibility, and stress all increase gas consumption. In these situations, shorten the dive or increase your reserve and conservatism factor.

Good gas planning is not about staying longer — it’s about ending every dive relaxed, unhurried, and with gas to spare.

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