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Open a CPAP report and you will see average, median, 95th percentile and maximum pressure. Of the four, the 95th percentile is the one most clinicians look at first. Here is what it means without the statistics.
Key takeaways
- P95 is the pressure you stayed at or below for 95 percent of the night.
- It ignores one-off spikes, so it is a steadier guide than the maximum.
- If P95 hugs the top of your set range night after night, tell your clinician.
What P95 means
Line up every minute of the night from lowest pressure to highest. The 95th percentile is the value that 95 percent of those minutes sit at or below. Put another way, it describes how much pressure your airway needed during the hardest stretch of the night, without letting a single brief spike set the number. Our short guide to what is P95 pressure goes into why this percentile is used.
Why not the maximum, or the average
The maximum is a single moment: a cough, a roll onto your back or a short leak can briefly push it up to your ceiling even on a perfectly good night. The average blends in the easy minutes and hides the demanding ones. P95 sits between: stable enough to compare night to night, and sensitive enough to notice when your needs change. Note that Philips machines report a 90th-percentile figure instead, so check which one your machine uses before comparing numbers across brands.
| Measure | What it tells you | Weakness |
|---|---|---|
| Average | Where pressure usually sits | Hides the demanding stretch |
| Median | The middle of the night | Same weakness as the average |
| 95th percentile (P95) | Where you needed to be most of the hard part | Needs a baseline to interpret |
| Maximum | The single highest moment | One spike can set it |
Reading P95 against your range
On an auto machine your clinician sets a minimum and a maximum. A P95 comfortably inside the range is what you want to see. A P95 that sits at the ceiling most nights suggests the machine may want more room, and that is a conversation for your clinician, never something to change yourself. Pressure readings rise and fall with leak and sleep position, so always read them with the leak line; why your pressure climbs at 4 a.m. shows a typical example.
Not medical advice. Apnealytics is a tracking and coaching tool, not a diagnostic device. Machine-estimated numbers are not a clinical diagnosis; talk to your clinician about your therapy.
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Written by
Haniel Singh
Founder of Apnealytics. A CPAP user who builds software, not a sleep physician.
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