Best Nitrox Mix Calculator
Pick the most efficient nitrox mix for a target depth. This finds the highest oxygen percentage whose partial pressure still sits at your chosen ppO2 limit at that depth, which gives the longest no-decompression time the limit allows.
How to find the best nitrox mix
- Enter your planned maximum depth in metres or feet.
- Choose a maximum ppO2, usually 1.4 ata working or 1.6 ata contingency.
- Read the best oxygen percentage and have a blender prepare and analyse it.
Examples
30 m at ppO2 1.4
Depth 30 m, max ppO2 1.4
ata 4.0, best mix 35%
40 m at ppO2 1.4
Depth 40 m, max ppO2 1.4
ata 5.0, best mix 28%
Frequently asked questions
What is the best nitrox mix for a given depth?
It is the richest mix whose oxygen partial pressure reaches but does not exceed your ppO2 limit at that depth. Richer than that breaches the limit; leaner gives less benefit. The depth becomes the mix MOD.
How is the best mix calculated?
First find ambient pressure: ata is depth in metres over 10 plus 1, or depth in feet over 33 plus 1. The best oxygen percentage is then maxPpO2 divided by ata, times 100, capped at 100.
Why does the calculator cap the mix at 100%?
Oxygen cannot exceed 100% of a mix. In shallow water the formula can suggest more than 100%, which simply means even pure oxygen stays under your ppO2 limit at that depth.
Should I round the best mix up or down?
Round down to a slightly leaner standard mix so your real ppO2 stays under the limit. A blend of 31.7% is usually filled as EAN31, never rounded up to EAN32.
Can I dive a mix without verifying it?
No. This is a training and planning aid only. Get certified for nitrox, analyse every cylinder yourself, follow your training and defer to your dive computer underwater.
Related tools
Nitrox MOD Calculator
Find the maximum operating depth of any nitrox mix in metres and feet. Set the oxygen percentage and your ppO2 limit, default 1.4 ata. Free planning aid.
Equivalent Air Depth Calculator
Convert a nitrox dive to its equivalent air depth in metres or feet. Enter the oxygen percentage and depth to read the EAD for table and computer planning.
Oxygen Partial Pressure Calculator
Calculate the oxygen partial pressure of a dive gas at depth in metres or feet. Enter the oxygen percentage and depth to check the ppO2 against the 1.4 limit.
Scuba Air Consumption Calculator
Work out your surface air consumption rate from a dive. Enter start and end pressure, time and depth to get a SAC rate in psi or bar per minute for planning.