Air Consumption Calculator

SAC, autonomy, reserve — Plan your dives with precision.

Interactive tool Planning

⚠️ Warning — This tool is for informational purposes only and does not replace proper dive training or a dive computer. Your actual consumption varies with effort, stress, temperature and fitness. Always maintain sufficient safety reserve, minimum 50 bars. Formula based on Boyle's law.

Calculator

Enter your dive parameters to estimate air consumption and autonomy.

Tank volume (L) Total tank volume

Start pressure (bar) Pressure at the start

End pressure (bar) Planned minimum pressure

Depth (m) Average dive depth

Duration (min) Time at depth

Reserve (bar) Safety reserve

Quick scenarios Pre-fill fields to test typical cases.

All fields are required.

SAC Rate

—

Surface-normalized rate

Air Used

—

Total air used

Remaining Autonomy

—

Above selected reserve

Assessment

—

SAC and reserve

Understanding air consumption

SAC is your air consumption rate normalized to surface pressure. It is an essential personal metric for comparing dives and planning reserves.

Formula

SAC = (P_start − P_end) × Tank_volume / (Duration × Absolute_pressure) Remaining autonomy = (P_end − Reserve) × Tank_volume / (SAC × Absolute_pressure)

Absolute pressure = 1 + depth/10. At 20 m, you breathe about 3 times more air than at the surface. The displayed autonomy is the gas remaining above the selected reserve.

Interpret your result

Use these guidelines to understand your SAC rate without replacing conservative planning.

Low SAC

< 15 L/min

Excellent efficiency. You usually have a more comfortable gas margin.

Moderate SAC

15–20 L/min

Average consumption. Plan a conservative reserve and monitor your air.

High SAC

> 20 L/min

Can come from stress, current, cold or heavy workload.

1. Compare profilesYour SAC is more useful compared across multiple dives than as an isolated value.

2. Monitor your reserveZero remaining autonomy means you are already at or below the reserve.

3. Keep a marginCold, current, stress or assisting a buddy can sharply increase consumption.

Frequently asked questions

Why does my consumption change between dives?

Consumption depends on effort, stress, cold, current, weighting, experience and depth.

What reserve should I keep?

A simple rule is to surface with at least 50 bars. For more demanding dives, apply a more conservative margin according to your training and dive leader.

Is a 12L tank enough for my dives?

For many recreational dives, yes, if your SAC is normal and the depth/duration are reasonable.