Why Your CPAP Mask Leaks and How to Fix It

Step 1: Understand Why Leak Matters

Your CPAP machine works by maintaining a specific air pressure to keep your airway open. When your mask leaks, the machine can't maintain that pressure, and your therapy suffers.

A moderate leak might not feel like a problem (you may not even notice it while sleeping), but your data will show the impact: more respiratory events, pressure fluctuations as the machine tries to compensate, and reduced therapy effectiveness.

If you suspect the mask category itself is the wrong fit for your face or sleep position, the Mask Finder Quiz is a 30-second cross-check before you invest more time in fitting tweaks.

Step 2: Understanding Your Leak Data

Before troubleshooting, it helps to understand what your machine is actually reporting and what the numbers mean.

Large Leak vs Intentional Vent Leak

Every CPAP mask has built-in exhalation ports (small holes or a diffuser vent) that allow carbon dioxide to escape. This is called intentional leak or vent leak, and it is completely normal. Your machine accounts for this and subtracts it from the total airflow.

What your machine reports as "leak" or "leak rate" is the unintentional leak, the air escaping around the mask seal that shouldn't be escaping. This is the number you need to pay attention to.

On ResMed AirSense machines, the leak value on your SD card data represents unintentional leak in liters per minute (L/min). Some other machines may report total leak (intentional + unintentional), so be sure you know which value you're looking at.

Normal Leak Ranges

Occasional spikes during position changes are normal. It's your typical leak and consistent patterns that matter. Brief breaks are read separately. When your leakiest stretches, the top 5% of the night, run above 36 L/min, your night view says your leak ran high for part of the night.

Reading Your Leak Chart

When you view your leak data in a tool like CPAP Clarity, you'll typically see a graph showing leak rate over the course of the night. Here's what common patterns mean:

• Flat line near zero. Excellent seal all night. Nothing to fix.
• Brief spikes returning to baseline. Normal position changes. Your mask shifted momentarily, then resealed.
• Sustained elevation for hours. Your mask likely shifted into a poor position and stayed there. This often happens after a position change in deep sleep.
• Gradual increase throughout the night. Your straps may be loosening as you sleep, or facial muscle relaxation is changing the seal.
• High leak from the start. The mask was not properly fitted at bedtime.

Step 3: Try Quick Fixes First

1. Adjust Your Mask Straps

The most common cause of leak is straps that are too loose or too tight. Over-tightening actually makes leaks worse. It distorts the cushion and creates gaps.

The right tension. Loosen all straps, place the mask on your face, then tighten just enough that you can slide one finger under the strap. The cushion should seal with minimal pressure. If your mask leaves red marks or pressure sores, see our guide on getting a better fit without over-tightening.

2. Clean Your Mask Cushion

Facial oils build up on the silicone cushion overnight. After a few days, the surface becomes slippery and won't seal properly.

Wipe the cushion with a damp cloth each morning. Once a week, wash it with warm water and mild soap and let it air dry completely.

3. Check Your Sleep Position

If your leak data shows spikes at specific times, you're likely rolling onto your mask. Side sleepers often push the mask against the pillow, breaking the seal.

A few things help.

• CPAP-specific pillows have cutouts for the mask
• A positional therapy pillow can keep you from rolling
• Consider a nasal pillow mask if you're a restless sleeper

If position-based leak is your pattern, start with do you need a CPAP pillow? to confirm the diagnosis in your own leak data, then our guide to the best CPAP pillows for side sleepers covers the specific cutout designs that keep the mask seal intact when you turn over.

4. Address Mouth Breathing

If you use a nasal mask and breathe through your mouth during sleep, air rushes out through your mouth, registering as a large leak.

There are three common fixes.

• A chin strap keeps your jaw closed during sleep. Fisher & Paykel says a chin strap can be risky if you have a deviated septum or a blocked nose, so ask your provider first.
• A full-face mask covers both nose and mouth.
• Mouth tape is something some users try to keep their lips sealed. Discuss it with your doctor first.

Step 4: Replace Your Cushion If Worn

Mask cushions are consumable. They wear out. ResMed gives two sets of intervals. Its US supply guidance puts cushions and nasal pillows at every month. Its Australian patient guidance puts them at:

• Silicone cushions, about every 6 months
• Memory foam cushions, every month

Replace any cushion or pillow sooner if it is worn, torn or no longer seals. Medicare's usual maximum is up to 1 full face cushion, or 2 nasal cushions or sets of nasal pillows, a month; see the CPAP supply replacement schedule for both.

Signs your cushion needs replacing:

• Leak rate has gradually increased over weeks
• The silicone feels stiff, sticky, or has visible wear marks
• You need to tighten straps more than you used to
• You can see daylight between the cushion and your face

A fresh cushion can dramatically improve your seal overnight, so reorder the OEM cushion for your mask model when it starts to leak.

Step 5: Consider a Different Mask

If you've tried all the quick fixes and leak is still a problem, your mask type or size may not be right for your face. Our CPAP mask types guide explains the differences between nasal, full face, and nasal pillow masks to help you choose.

Mask Types

Nasal masks cover just the nose. Best for people who breathe through their nose and don't need high pressures. Most common type.

Nasal pillows sit at the entrance of your nostrils. Minimal contact, great for side sleepers, but can be uncomfortable at higher pressures. The ResMed AirFit N30i is a nasal cradle option whose hose connects at the top of your head, out of the way for side sleepers.

Full-face masks cover nose and mouth. Best for mouth breathers and people who need higher pressures. More prone to leak due to larger sealing surface. The ResMed AirFit F20 is one of the most widely used full-face masks, known for a comfortable seal across a range of face shapes.

Getting the Right Size

Most masks come in 2-4 sizes. The wrong size is a common cause of persistent leak. Many suppliers offer sizing guides or fitting tools. Use them.

Step 6: Track Your Leak Data

Your CPAP machine records leak rate throughout every session. Analyzing this data helps you identify patterns:

• Consistent leak all night → Mask fit/size issue
• Leak spikes at specific times → Position changes
• Gradually increasing leak over weeks → Cushion wearing out
• Leak correlating with events → Mask dislodging during apneas

CPAP Clarity shows your leak rate chart alongside your events, so you can see exactly how leak affects your therapy. Analyze your data free →

To see which part of the night your highest-leak minutes keep landing in, the leak pattern finder reads your latest 30 ResMed nights in your browser and names the third of the night that holds most of your minutes at or above 24 L/min, with the counts.

Step 7: Mask-Specific Troubleshooting

Different mask types have different common leak points. Here are targeted tips for each.

Nasal Masks

Nasal masks cover just the nose. Common leak issues:

• Bridge of the nose. This is the most frequent leak point. The nasal bridge area has less soft tissue for the cushion to seal against. Try adjusting the top strap slightly tighter while loosening the bottom straps.
• Mouth leak. If you breathe through your mouth during sleep, air rushes out and registers as a large leak. A chin strap or switching to a full-face mask may help.
• Side of the nose. If air blows into your eyes, the mask is leaking upward along the sides of your nose. The mask may be too wide for your face, or the headgear needs repositioning.

Full-Face Masks

Full-face masks cover both nose and mouth. They have a larger sealing surface, which creates more opportunities for leak.

• Chin area. The lower portion of the mask can lose its seal if your jaw drops open or shifts during sleep. Make sure the lower straps are snug (but not overtight) and positioned correctly.
• Cheek area. Smiling, talking, or jaw movement during sleep can break the seal along the cheeks. If this is a recurring issue, a mask with a smaller under-nose design (like the ResMed AirFit F30) may reduce the sealing area and improve stability.
• Higher pressures. Full-face masks are more susceptible to leak at higher pressure settings because of the larger internal volume. If your prescribed pressure is 14 cmH2O or higher and leak is persistent, discuss mask options with your provider.

Nasal Pillow Masks

Nasal pillows sit at the entrance of your nostrils. They have minimal contact with your face, which can be both an advantage and a challenge.

• Pillow size. Nasal pillows are extremely sensitive to sizing. Even one size off can cause significant leak. Most brands include multiple pillow sizes. Try each one.
• Nostril shape. Asymmetric nostrils (which are common) can cause one side to seal better than the other. Repositioning the headgear slightly can help equalize the seal.
• High pressure discomfort. At 14 cmH2O or higher, nasal pillows can become uncomfortable and harder to seal. If you need higher pressures, a nasal mask or nasal cradle design may work better.

Step 8: When to Replace Parts vs When to Adjust

Not every leak problem requires new equipment. Here's how to tell whether a fit adjustment will solve the issue or whether parts need replacing.

Signs That Fit Adjustment Will Fix It

• Leak appeared suddenly after a change (new sleeping position, different pillow, headgear shifted)
• Leak only happens in certain sleep positions
• The cushion still looks and feels supple
• You recently changed something about your setup

Signs That Parts Need Replacing

• Cushion feels stiff or tacky. Silicone degrades over time, losing its softness and ability to conform to your face.
• Visible wear. Flattened areas, cracks, discoloration, or permanent compression marks.
• Gradual leak increase over weeks. If your leak rate has been slowly climbing and strap adjustments don't help, the cushion has likely worn past its effective life.
• You need progressively tighter straps. This is a classic sign of cushion wear. A new cushion seals with light pressure. A worn cushion needs to be pressed harder into your face.
• Headgear has lost elasticity. Straps that are stretched out can't maintain proper tension. Replace the headgear.

Replace cushions on schedule (ResMed's US supply guidance says every month; its Australian guidance says about every 6 months for silicone and every month for memory foam), and sooner when one is worn. A fresh cushion is one of the simplest and most effective improvements you can make. If new parts did not stop it, see what new parts cannot fix.

Step 9: When to Involve Your Provider

Most leak issues can be resolved with the steps above. However, there are situations where you should involve your sleep specialist or equipment provider.

• Persistent leak despite troubleshooting. If you have tried multiple adjustments, replaced your cushion, and leak remains consistently at or above 24 L/min, your provider can evaluate whether a different mask type or size is needed. For a broader symptom-first decision tree across leak, rainout, pressure-feel, and other CPAP issues, see the CPAP troubleshooting guide. If the leak is still there after you have replaced the mask, hose and headgear, what to check when a CPAP still leaks after replacing everything covers the causes new parts cannot fix.
• Leak accompanied by high AHI. If elevated leak and increased respiratory events show up on the same nights, that is worth showing your provider, who can review your data and decide whether anything should change.
• Skin irritation or pressure sores. If you are over-tightening your mask to compensate for leak and developing skin issues, stop. Your provider can recommend alternatives including mask liners, different mask styles, or custom fitting.
• Recent facial changes. Weight changes, dental work, or facial surgery can change the fit of your mask. Your provider can help you get re-fitted.
• Discomfort at your prescribed pressure. If leak problems seem connected to high pressure settings, never adjust your pressure without consulting your provider. They can evaluate whether EPR adjustments, pressure changes, or a different mask style would help.

What You Might Need

If you're troubleshooting leak, here are the supplies that most often solve the problem:

• Replacement mask cushions (the single most common fix)
• CPAP masks (if your current mask type isn't right for your face)
• CPAP pillows for side sleepers (mask-friendly cutouts prevent seal breaks)

Leak Is the Most Fixable Problem in CPAP

Leak is the most fixable problem in CPAP therapy. Start with strap adjustment and cushion cleaning, replace worn cushions on schedule, and use your data to identify patterns. If basic troubleshooting doesn't resolve the issue, your sleep specialist can help determine the right mask type and fit for your anatomy. A well-sealed mask is the foundation of effective treatment.

Primary Sources

• ResMed AirSense 10 Clinical Guide (opens in new tab). Source for the 24 L/min line, and for exactly how far it stretches. ResMed publishes one leak criterion: mask seal is "Good" when "the 70th percentile leak is less than 24 L/min". The table above reads that line against your night's typical (median) leak, the same way your night view does, and that transfer is ours, not ResMed's. The 15 L/min edge, and the 36 and 48 L/min lines for brief breaks, are this site's own. Nothing in the ResMed guide contains a "large leak" threshold at all. Other manufacturers publish different figures, so check your own machine's manual.