CPAP Mask Sizing: Get the Right Fit First Time

Written by the Morpheus Healthcare team. Medically reviewed by Dr. Ashok Rajput.

Quick answer: There are three CPAP mask families — nasal masks, full face masks, and nasal pillows — and the right one depends on how you breathe, sleep and live (ResMed — choosing the right CPAP mask). Size is determined with manufacturer sizing gauges, and — crucially — a Medium in one mask is not a Medium in another (ResMed sizing guide). A professional fitting, done in your sleeping position with the air on, gets it right the first time.

The mask is the therapy

Here’s what a decade of fitting masks in Delhi has taught us: people don’t abandon CPAP because of the machine. They abandon it because of the mask — leaks that hiss at 2 am, red marks at breakfast, straps cranked painfully tight to fight a seal that was never going to work. The machine pushes air; the mask is where therapy meets your face. Get it right the first time and everything else gets easier.

The three mask types, and who each suits

Per ResMed’s own guidance:

  • Nasal masks deliver air over the nose only. A balanced middle path — smaller than a full face mask, more stable than pillows. Under-the-nose designs reduce marking and suit people who read or wear glasses in bed.
  • Full face masks cover nose and mouth. Best if you breathe through your mouth at night or have nasal blockage issues such as allergies or a deviated septum.
  • Nasal pillows seat two soft inserts at the nostrils. The lightest, most minimal option — popular with people who feel closed-in by larger masks or want a clear field of vision.

Beards deserve a mention: masks with memory-foam-type cushions such as ResMed’s AirTouch line tend to seal better over facial hair.

How sizing actually works — and why guessing fails

Manufacturers publish sizing gauges/templates — printed measures held against the nose or face to read off your size. Three things most first-time buyers don’t know (ResMed sizing guide):

  1. Templates must be printed at exact scale. Print with “fit to page” on and the ruler is wrong — and so is your size.
  2. Sizing is not consistent across masks. Different models size differently even within one brand. Your size in one mask tells you little about another.
  3. Fit changes when you lie down. ResMed’s guidance is explicit: a mask that seals sitting up may leak lying down, because facial muscles relax — so fit the mask in your usual sleeping position, and adjust the headgear as loose as possible while still sealing. Over-tightening is the most common self-fitting mistake; it causes leaks and pressure sores.

Also: fit with the air flowing. Cushions like ResMed’s are designed to seal under pressure, which is why a mask can feel wrong when you try it “off the machine” and fine once therapy starts.

Why a professional fitting beats trial-and-error

Buying masks by guesswork online means paying full price to experiment on your own face. Our alternative is simple: a certified-coach mask fitting — in person in Delhi or guided over video. Your coach measures with proper gauges, tries the shortlist that matches your breathing style and sleep position, fits it lying down with the machine running, and teaches you the strap discipline that keeps the seal without the squeeze.

We won’t promise you a swap-until-happy scheme — we’d rather do the unglamorous work of getting the size right before you pay. If you’d like to be extra sure of the whole setup, our paid trial/rental is credited toward your purchase, and every mask we sell is a genuine unit with the full manufacturer’s warranty.

Browse our mask collection, or if you’re starting from scratch, begin with a home sleep test and pair the right mask with the right machine. Fitting appointments are arranged via our service page.

FAQ

Q1. Which CPAP mask type is best for mouth breathers? A full face mask, which covers nose and mouth, is generally recommended for mouth breathers or people with nasal obstruction such as allergies or a deviated septum.

Q2. Are mask sizes standard across brands and models? No. Sizing differs between mask models even within a brand — a Medium in one is not a Medium in another. Always size per-mask, with that mask’s own gauge.

Q3. How tight should CPAP headgear be? As loose as possible while still maintaining a seal. If you need to crank the straps to stop leaks, the size or style is wrong — tightening is not the fix.

Q4. Why does my mask leak when I lie down but not when I sit up? Facial muscles relax when you lie down, changing the seal surface. Fit and adjust your mask in your usual sleeping position.

Q5. I have a beard. Can I still seal a CPAP mask? Usually, yes. Cushion materials matter — memory-foam-style cushions (e.g. ResMed AirTouch) tend to perform better over facial hair. A fitting will settle it quickly.

Q6. What if my face shape doesn’t suit the mask I chose? That’s exactly what the fitting is for — we shortlist by face shape, breathing style and sleep position before you pay, and masks are covered by the manufacturer’s warranty against manufacturing defects via the authorized service centre.

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