How to Choose a CPAP Machine

CPAP stands for continuous positive airway pressure. Most machines look alike from the outside, but they differ in how they set pressure, how they add moisture to the air, how much they weigh and how they record data. This guide walks through each difference and ends with a checklist. It covers the equipment only and gives no health advice.

We sell equipment, not medical advice. As our product pages state, customers will need to provide prescriptions for respiratory devices, and for CPAP and BiPAP equipment a valid prescription is required where applicable. Pressure settings come from your prescriber, so talk to them or your equipment provider about which features suit you.

What is the difference between fixed and auto-adjusting pressure?

Fixed-pressure CPAP. The machine delivers air at one pressure setting all night. These machines are usually simpler and often cost less.

Auto-adjusting machines (often called APAP or auto CPAP). The machine changes the pressure through the night within a minimum and maximum set by the prescriber. Many auto machines can also run in a fixed-pressure mode.

Both types commonly offer a ramp, which begins below the set pressure and climbs to it over a period you choose, and many offer an exhale setting that eases the pressure a little as you breathe out. Names for these features differ by manufacturer. Bilevel (BiPAP) machines, which use two separate pressures, are a different category and are not covered here.

Do you need a humidifier?

Most current machines either have a heated humidifier built in or accept one that clips on. The humidifier warms water in a small chamber so the air picks up moisture before it reaches the mask. Points to compare:

• Built-in or separate: built-in units make a single compact package; separate units can be left at home.
• Water chamber: check how easy it is to fill and clean, and which water the manufacturer asks you to use (often distilled).
• Heated tubing: an optional heated hose keeps the air warm on its way to the mask and helps limit condensation in the tube. Heated tubes usually fit only one machine family.
• Off switch: on most machines the humidifier can be turned off or removed.

How do size and weight compare for travel?

Full-size machines are made to sit on a nightstand and usually include the humidifier. Travel machines are much smaller and lighter, and many leave out the water humidifier; some accept a waterless insert instead. If you plan to travel often, compare the weight with and without the humidifier, the overall size, and whether a carry bag is included.

How quiet is a CPAP machine?

Manufacturers publish a sound level in decibels (dBA), measured in a standard lab test. Lower numbers are quieter, but compare figures from the spec sheets rather than marketing copy, and keep in mind that the mask's vent and how well it fits also affect what you hear in the room.

What data and app features are available?

Many machines record usage hours, mask leak and pressure data. Depending on the model, data is stored on a memory card or sent through a built-in wireless connection to a manufacturer app or portal, where it can be shared with your prescriber or equipment provider. Before you buy, check:

• How data is stored and transferred (memory card, Bluetooth or cellular).
• Whether a phone app is offered and whether it needs an account.
• Who can see the data, and the manufacturer's privacy terms.

Will your mask work with the machine?

Most masks connect to CPAP tubing with a standard connector, so a full face, nasal or nasal pillows mask from one brand will usually fit a machine from another. Tubing is where differences show up: standard and slim tubes have different inner diameters, and heated tubes are usually made for one machine family. Some machines also have a setting for the mask type. Our CPAP masks guide explains the three mask styles and sizing, and replacement parts are in our masks and accessories collection.

What power and travel options should you check?

• Power supply: many machines ship with a power supply rated for 100-240 V, so they work abroad with a plug adapter. Check the label on the unit.
• DC power: some manufacturers sell a DC cable for 12 V or 24 V sources such as a vehicle or camping battery.
• Batteries: external batteries are available for some models. Run time is shorter with the humidifier or heated tube on.
• Air travel: many manufacturers state that their machines meet FAA requirements for use on board. Check the manufacturer's statement and ask your airline before you fly.

How do the main features compare?

What should you check before you buy?

• Have your prescription ready.
• Choose fixed or auto-adjusting pressure based on your prescription.
• Decide whether you want a built-in humidifier and heated tubing.
• Compare weight and size if you travel.
• Compare the published dBA figures.
• Check the data, app and privacy terms.
• Confirm the tubing type and that your mask style is supported.
• Check the power supply, DC and battery options.
• Read our returns policy before ordering.

Talk to us

Have a question about a machine or its accessories? Call 1-877-861-8000, Monday-Friday, 9 AM-6 PM Pacific, or email contactus@medsupplynow.com. You can see the machines we list in our CPAP machines collection and related equipment in CPAP, BiPAP and respiratory.

Related guides

You may also find these useful: CPAP masks explained and home health monitors. For every topic we cover, see the buyer's guide hub.

Frequently asked questions