CPAP Pressure Calculator

The CPAP Pressure Calculator estimates optimal therapeutic pressure in cm H₂O based on your BMI, AHI, and sleep factors. This tool helps Obstructive Sleep Apnea patients manage their therapy effectively. Whether you are adjusting your home machine, preparing for a specialist visit, or tracking your sleep health, this calculator provides a reliable estimate to improve your rest.

Enter your weight in kilograms
Enter your height in centimeters
Number of apnea/hypopnea events per hour (from sleep study)
Enter your age in years

How CPAP Pressure Is Calculated

CPAP pressure represents the air force needed to keep your airway open during sleep. We calculate this using a weighted clinical algorithm.

Pressure = 4 + (AHI × 0.03) + (BMI × 0.1) + Position Factor + Mask Factor + Comorbidity Factor

Where:

  • Base: Starting pressure of 4 cm H₂O.
  • AHI: Events per hour indicating severity.
  • BMI: Body Mass Index affecting neck tissue.
  • Factors: Adjustments for position, mask, and health.

First, we find your Body Mass Index (BMI) because excess neck tissue often requires more force to keep the throat open. Then, we add pressure points based on your Apnea-Hypopnea Index (AHI) severity to match your specific event frequency. Finally, we apply adjustments for gravity effects from your sleep position, potential leaks from your mask type, and other health needs. This method offers a reliable starting point closely matching professional titration studies.

What Your CPAP Pressure Means

Your result shows the specific air intensity required to stop your breathing pauses and ensure you get enough oxygen while sleeping.

Mild Obstruction (4.0 – 6.0 cm H₂O)

You likely have positional apnea or minor symptoms. A nasal pillow mask is usually comfortable enough to seal effectively at these lower pressures, making therapy easier to start.

Moderate Support (7.0 – 10.0 cm H₂O)

This is the most common therapeutic range. You may benefit from using a heated humidifier to prevent dryness as airflow increases, which helps ensure long-term comfort.

High Pressure Needs (11.0+ cm H₂O)

Your airway collapses significantly under gravity. You might need a full-face mask to maintain a seal and prevent aerophagia, or swallowing air, during sleep.

Pro Tip

If you lose a significant amount of weight, recalculate your needs to see if a lower, more comfortable pressure is possible.

This tool is for educational purposes only and is not a substitute for a medical diagnosis or prescription. Always consult a qualified sleep specialist before starting or changing your therapy settings.