The Best Trimix tool can help you decide on the mix you want to use for a given dive profile. Simply enter the Planned Depth, Desired Maximum Partial Pressure of Oxygen (PPO2) and Desired Bottom END to see the mix that will meet the PPO2 at the planned depth and have an END matching your request. Remember that this mix will maximize your (theoretical) no decompression limit but does not consider your oxygen exposure limits. It may be better to extend your decompression time instead of getting close to your oxygen exposure limits.
Oxygen is treated as a narcotic gas for END related calculations by default. A setting is provided in the “Settings” tab (More->Settings) to change this behavior if you prefer to not treat oxygen as narcotic. Your suggested mixes will contain less helium is you choose not not treat oxygen as a narcotic gas.
Tap on the bookmark icon to recall a previously saved calculation or to save this calculation for future use.
You can easily make the calculations for salt water or fresh water and in Metric or Imperial/US by selecting the “Settings” tab (if it is not visible on the current screen select “More”) and changing the appropriate settings. You can also adjust some of the warnings offered by the application in the settings tab. The next version of the software will also provide a setting for treating oxygen as a narcotic gas.