AHI (Apnea-Hypopnea Index) Calculator

Health

The AHI Calculator works out the Apnea-Hypopnea Index — the average number of apnea and hypopnea events per hour of sleep — used to grade obstructive sleep apnea severity. AHI = total events ÷ total sleep hours.

Rates and fees change frequently. Always confirm the current figures with the official authority before relying on this result.

Formula

AHI = Total Apnea and Hypopnea Events ÷ Total Sleep Hours
  • AHI is the average number of apneas (breathing pauses) and hypopneas (shallow breaths) per hour of sleep.
  • Formula: AHI = total events ÷ total sleep time in hours.
  • Severity grading: under 5 is normal, 5–15 mild, 15–30 moderate, and over 30 severe obstructive sleep apnea.
  • This is a screening estimate; a formal diagnosis requires a sleep study interpreted by a clinician.

Example Calculation

Inputs
  • Apnea + Hypopnea Events: 120
  • Total Sleep Time (hours): 8

With 120 events over 8 hours of sleep: AHI = 120 ÷ 8 = 15 events/hour, which falls at the moderate threshold.

Frequently asked questions

What is the Apnea-Hypopnea Index?
It is the average number of apnea and hypopnea events per hour of sleep, used to grade the severity of sleep apnea.
How is AHI severity classified?
Under 5 is normal, 5–15 is mild, 15–30 is moderate, and above 30 is severe obstructive sleep apnea.
What counts as an event?
An apnea is a near-complete pause in breathing and a hypopnea is a partial reduction in airflow, both typically lasting at least 10 seconds.
Where do I get the event count?
From a sleep study (polysomnography) or home sleep test, which records the total apneas and hypopneas.
Is this a diagnosis?
No. It is a screening estimate; sleep apnea must be diagnosed by a qualified clinician.