MOD / EAD / END Calculator

Gas Calculators — Key Features

• MOD calculator — find the maximum safe depth for any oxygen percentage
• EAD calculator — convert nitrox dives to equivalent air depth
• END calculator — determine narcotic depth for trimix gases
• Best Mix finder — optimal oxygen percentage for your target depth
• Support for nitrox and trimix gas mixes
• Configurable PPO₂ limits for different diving scenarios

Gas Calculators — How It Works

Enter your gas mix (oxygen and optionally helium percentage) and the calculator instantly shows your MOD, EAD, and END. Use the Best Mix tool to find the optimal nitrox blend for a given depth. All calculations update in real time as you adjust parameters.

Why Use Our Gas Calculators?

• Instant results — calculations update as you type
• All essential gas calculations in one place
• Supports both nitrox and trimix gas mixes
• Clear visual feedback on safety limits

Gas Calculators — Frequently Asked Questions

What is MOD and why does it matter?

MOD (Maximum Operating Depth) is the deepest depth at which a gas mix can be safely breathed based on its oxygen content. Exceeding the MOD risks oxygen toxicity, which can cause seizures underwater.

What's the difference between EAD and END?

EAD (Equivalent Air Depth) tells you the equivalent depth on air for decompression purposes with nitrox. END (Equivalent Narcotic Depth) tells you the depth at which you'd feel the same narcosis on air — mainly relevant for trimix dives with helium.

Is this calculator free?

Yes! The MOD/EAD/END calculator is completely free to use. Just create a free account to get started and access all free tools including the unit converter and gradient factors calculator.

What ppO2 limit should I use?

The standard limit is 1.4 bar for the working portion of a dive and 1.6 bar for decompression stops. These limits are widely accepted by training agencies to minimize the risk of central nervous system oxygen toxicity.

Can I calculate for trimix gases?

Yes. The END calculator fully supports trimix by accounting for the helium fraction, which reduces narcosis. Enter your oxygen and helium percentages to see the equivalent narcotic depth compared to breathing air.

How does nitrox affect my no-decompression limits?

Nitrox extends your no-decompression limits because the higher oxygen percentage means less nitrogen. For example, EAN32 at 30 meters gives you the same nitrogen loading as air at about 24 meters, significantly increasing your safe bottom time.