Finding the right size and fit for your CPAP masks is just as important as choosing the right machine. A poorly fitted mask can cause air leaks, discomfort, and even reduce therapy effectiveness. Whether you’re shopping for CPAP masks UK or adjusting your current setup, this guide will help you achieve a secure, comfortable, and leak-free seal.
According to the NHS sleep apnoea guidance, a properly fitted mask improves comfort, reduces side effects like dryness or pressure marks, and increases long-term adherence to therapy.

Your mask is the interface between your face and the airflow generated by the CPAP device. The wrong size can cause leaks around the nose or mouth, skin irritation, and disrupted sleep. On the other hand, a well-fitted mask machine face ensures stable pressure and consistent oxygen flow throughout the night.
For high-quality mask options, visit the CPAP Masks Category on Sleepap.co.uk.
Each mask style requires a slightly different approach to sizing and fitting. Here’s a quick overview before measuring:
For a detailed comparison between mask types, see our guide: CPAP Mask Types and Fit: Nasal Pillow, Nasal, and Full Face Designs.

Manufacturers often provide printable sizing guides to help you find your perfect fit. As a general rule:
Always try on your CPAP machine mask while lying down — your face shape changes slightly when reclining.
Still unsure? Explore our range of CPAP Masks UK or visit our full website at Sleepap.co.uk for expert support.

Changes in weight, facial structure, or therapy pressure can affect mask performance. If you notice air leaks, soreness, or marks after sleep, it’s time to reassess sizing or switch styles. Some patients also find Auto-adjusting devices easier to use — see our guide: APAP Machine Explained vs Standard CPAP.
Choosing the right size for your CPAP masks ensures both comfort and effective sleep apnoea treatment. With the correct fit, you’ll prevent leaks, sleep more soundly, and experience lasting results from your therapy. Visit CPAP Masks UK on Sleepap.co.uk to find your perfect mask today.
What does a CPAP mask do for you?
A CPAP mask delivers steady air pressure from your machine to keep your airway open while you sleep, preventing apnoea events and snoring.
How do I know what size mask I need?
Use a sizing guide provided by your mask manufacturer or measure the height and width of your nose and mouth area. Try on the mask while lying down to check for a secure seal without pressure.
What is the easiest CPAP mask to get used to?
Most new users find nasal pillow masks easiest to adapt to, as they’re lightweight and have minimal facial contact.
What is the best sleeping position for apnea?
Side sleeping is often best because it helps keep the airway open and reduces snoring or blockages.
Which CPAP mask is best for side sleepers?
Nasal pillow masks or small nasal masks work best for side sleepers because they allow more movement and less bulk against the pillow.