Oxygen exposure tool
CNS Oxygen Clock Calculator
Estimate CNS oxygen exposure over multiple constant-depth Nitrox dives and account for recovery during surface intervals.
Multiple divesExposure limits90 min half-life
Calculator
Track your oxygen clock.
Add dives in order. Each dive contributes CNS exposure from ppO₂ and time; surface intervals reduce retained CNS before the next dive.
What the result means
The calculator updates instantly from the values you enter and shows the core planning result in the dark result card.
Use conservative inputs
Use realistic values from your own diving and leave a practical margin for changes in workload, conditions and equipment.
Verify before diving
Treat this page as an educational reference and cross-check the result with your training, analysed gas and an appropriate dive-planning method.
Planning reference only. These calculators are educational reference tools, not a substitute for training, a properly configured dive computer, analysed breathing gas or an approved dive plan. Use conservative values and follow the procedures of your training agency and dive operation.