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Understanding Your CPAP Prescription and Pressure Settings
A CPAP prescription names the device type, the pressure in cm H2O (or a minimum and maximum for auto CPAP), humidification and a mask. You can adjust comfort settings like ramp, humidity and exhale relief yourself, but the prescribed pressure or range should only be changed by your prescribing clinician.
What is on a typical prescription
Expect to see: device type (CPAP, APAP or bilevel), pressure in centimeters of water (cm H2O), or a minimum and maximum pressure for auto mode, heated humidification, a mask type or 'mask of patient choice', and the length of need, often written as 99 months meaning lifetime.
For bilevel, you will see two numbers: IPAP (inhale) and EPAP (exhale). Some prescriptions also specify a heated tube and exhale relief settings.
What the pressure number means
Pressure is the force of air needed to keep your airway open. Typical machines can deliver about 4 to 20 cm H2O. Your number was chosen from a lab titration, an auto CPAP trial, or your clinician's judgment.
A higher number is not a worse diagnosis. Pressure need depends on airway shape, sleep position, weight, nasal congestion and other factors.
Settings you can adjust yourself
Patient comfort settings are designed for you: ramp time and ramp start pressure (on many machines), humidity level, tube temperature, exhale relief level (EPR or Flex) on many models, and mask type selection so the machine calculates leak correctly.
If you change mask style, update the mask type in the machine's menu. It helps the machine estimate leak accurately.
Settings that belong to your clinician
Therapy pressure, auto minimum and maximum, mode and bilevel pressures are clinical settings. Changing them without guidance can undertreat your apnea or create new problems, such as central apneas or swallowed air.
If you think the pressure is wrong, look at a few weeks of data (AHI, leak, hours) and bring it to your clinician. They can adjust settings remotely on many connected machines.
Keep copies
Store a photo of your prescription and sleep test summary on your phone. You will need them to buy masks and supplies, switch suppliers, or get help when traveling.
Prescriptions for supplies may need renewing according to your insurer's or retailer's policy, so check the date on yours.
Frequently asked questions
What is a normal CPAP pressure?
There is no normal number; it is whatever treats your airway. Machines typically range from about 4 to 20 cm H2O, and your clinician sets your pressure or range from your test results and follow-up data.
Can I raise my pressure if I still snore?
Do not change it yourself. Snoring on CPAP can come from mask leak, mouth breathing or position as well as pressure. Bring your data to your clinician, who can change the setting if needed.
What does 'ramp' mean on my prescription?
Ramp lowers the starting pressure and builds up to your prescribed level over a set time so you can fall asleep. It is a comfort feature you can usually adjust yourself.
Does my prescription expire?
The diagnosis does not expire, but sellers and insurers may require a prescription dated within a certain period for supplies or a replacement machine. Check your supplier's or insurer's rules.
Sources
Last reviewed October 11, 2026. How we research · Report an error