User Guide
Nitrox Helper
Overview
Nitrox Helper has five tabs along the bottom of the screen. The first four are calculators; the fifth is Options. Each calculator tab displays a read-only water type indicator so you always know whether you are calculating for salt water or fresh water.
Best EAN Mix
Calculate the optimal oxygen percentage for your planned depth and PPO limit.
How to use:
- Enter your planned depth
- Set your PPO limit (default 1.4 bar)
- The best EAN mix percentage is calculated automatically
Use this result to request the right Nitrox mix at the fill station.
Maximum Operating Depth (MOD)
Determine the deepest safe depth for any Nitrox mix.
How to use:
- Enter your EAN mix (oxygen percentage)
- Set your PPO limit
- The maximum safe depth is calculated automatically
Never exceed the MOD for your mix. This is essential safety information for every dive plan.
Equivalent Air Depth (EAD)
Convert your Nitrox dive to an equivalent air depth for use with standard Recreational Dive Planner (RDP) tables.
How to use:
- Enter your EAN mix (oxygen percentage)
- Enter your planned depth
- The equivalent air depth is calculated automatically
The EAD will be shallower than your actual depth, allowing you to use standard air dive tables for planning.
Oxygen Partial Pressure (PPO)
Monitor your oxygen partial pressure at any depth with clear safety indicators.
How to use:
- Enter your EAN mix (oxygen percentage)
- Enter your depth
- The PPO is calculated automatically with a safety status indicator
Safety indicators:
- Safe — PPO is below 1.4 bar
- Caution — PPO is between 1.4 and 1.6 bar
- Danger — PPO exceeds 1.6 bar
Salt Water & Fresh Water
All four calculators account for water type. Salt water uses 10.0 metres per atmosphere; fresh water uses 10.3 metres per atmosphere. A read-only indicator on every calculator tab shows your current water type setting.
To change your water type, go to the Options tab.
Options
The Options tab (gear icon) lets you personalise the app:
- Language: Choose from 8 languages
- Theme: Pick from 16 colour themes
- Units: Metric (metres) or Imperial (feet)
- Water type: Salt water or fresh water
- Decimal places: 0–3 decimal places for depth and PPO results
- Subscription: Manage your Pro subscription
Per-Tab Unit Switching
Each calculator tab has a toolbar that allows you to switch between metric and imperial units independently. This is useful when you want to quickly check a calculation in a different unit system without changing your global preference.
Free & Pro
Nitrox Helper is free to download with a 30-day in-app trial. Monthly and Annual plans also include a 1-month introductory offer. After the trial, upgrade to Pro for unlimited calculations, all 16 colour themes, and all future features.
Disclaimer: This calculator is for discussion purposes only and is not intended for actual dive planning. Always refer to your certifying agency's Enriched Air Diving procedures to plan your dives. Accuracy cannot be guaranteed. Use at your own risk.