---
title: "Minimum gas"
description: "Working out rock bottom: the gas to keep so that you and an out-of-gas buddy can sort a problem at depth and ascend together."
---

> Documentation Index
> Fetch the complete documentation index at: https://docs.divelogic.ai/llms.txt
> Use this file to discover all available pages before exploring further.

# Minimum gas

import { MinimumGasScreen } from "@/components/react/ToolScreens";

Minimum gas answers *how much must I keep to get two of us up?* It works out
rock bottom: the gas a team needs to sort out a problem at depth and ascend
together, breathing hard, from one cylinder. Reach that pressure and the ascent
starts.

## What you enter

- **From** (m): the depth the problem happens at, usually the deepest point.
- **To** (m): 0 m for a direct ascent, or your first gas-switch depth.
- **Rate** (m/min): the ascent rate.
- **Divers**: how many breathe from this gas. Two is you and a buddy out of
  gas.
- **Stress factor** (×): how much faster than your RMV everyone breathes during
  the problem.
- **Sort it out** (min): time at depth before the ascent starts.
- **Stop** (min): time at the stop on the way.
- **RMV**, **Water** and your cylinder: shared with the other consumption
  tools. **Start** sets the rail, not the result.

The **Problem** group notes that two divers at a stress factor of 2 is the
usual rock-bottom assumption.

## Reading the result

- **Keep at least** (bar): the main figure. Its rail runs to your full **Start**
  pressure, marked solid, and turns red when rock bottom is more than a full
  cylinder.
- **Gas for the ascent** (L): the same reserve as free gas.
- **Ascent** (min): the time from **From** to **To** at your rate.
- **Average ambient** (bar): the pressure the ascent is breathed at, on
  average.

The figure adds three parts, each breathed by every diver at RMV times the
stress factor: the time to sort it out at the **From** depth, the ascent at its
average depth, and the stop at the **To** depth. A stop is never counted
shallower than 3 m, so a direct ascent still pays for its stop. Figures round
up: litres to the whole litre, pressure to the next 5 bar.

The verdict gives the instruction, for example *Start the ascent by 115 bar, so
you and a buddy out of gas can reach the surface.*

## What it does not include

- **Anything after the To depth.** Decompression below it, further stops and
  later gases are not counted.
- **The rest of the dive.** Rock bottom is a floor to keep, not the gas you
  need to dive.

## Next

- [Turn pressure](/tools/turn-pressure) plans the outbound leg around a reserve;
  compare its **Reserve** with this figure.
- [Contingency](/planning/contingency) re-plans a whole dive that runs long or
  deep.

Source: https://docs.divelogic.ai/tools/minimum-gas/index.mdx