AHI Calculator | Apnea-Hypopnea Index

Divide your total apneas and hypopneas by hours of sleep to find your apnea-hypopnea index (AHI) and its adult severity category.

Quick Facts

Formula
AHI = (apneas + hypopneas) / total sleep hours
Adult severity: under 5 normal, 5-15 mild, 15-30 moderate, 30+ severe.

Your Results

Calculated
Apnea-Hypopnea Index (AHI)
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Events per hour of sleep
Total respiratory events
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Apneas + hypopneas scored
Severity category
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Adult AASM classification
RDI (with RERAs)
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Events + arousals per hour

Ready

Enter your apnea and hypopnea counts and total sleep time, then calculate.

About the AHI Calculator

The apnea-hypopnea index (AHI) summarizes how often your breathing stops (apnea) or becomes shallow (hypopnea) during sleep. This calculator takes the event counts from a sleep study and the total sleep time, then reports the AHI in events per hour along with the standard adult severity category. It does not diagnose anything; it turns the raw numbers on a report into an easier-to-read rate.

The formula

AHI is a simple rate: the total number of apneas plus hypopneas, divided by hours of sleep.

  • AHI = (apneas + hypopneas) / total sleep time in hours.
  • Total sleep time is entered in minutes here and converted to hours (minutes / 60). It is actual sleep time, not time in bed.
  • RDI (respiratory disturbance index) adds respiratory effort-related arousals (RERAs): RDI = (apneas + hypopneas + RERAs) / hours. Leave RERAs at 0 and RDI equals AHI.

Adult severity categories

Sleep medicine groups adult AHI into four bands. These thresholds are for adults; pediatric criteria are lower.

  • Normal: AHI below 5 events per hour.
  • Mild: AHI from 5 to under 15.
  • Moderate: AHI from 15 to under 30.
  • Severe: AHI of 30 or more.

When to consult a professional

This calculator only performs arithmetic on numbers you already have. It does not diagnose sleep apnea, does not recommend treatment, and does not replace a sleep study. If your AHI is elevated or you have symptoms such as loud snoring, witnessed pauses in breathing, or daytime sleepiness, discuss the result with a licensed healthcare provider.

Frequently Asked Questions

What is the AHI formula?
The apnea-hypopnea index is the total number of apneas plus hypopneas recorded during sleep, divided by total sleep time in hours. For example, 40 apneas and 62 hypopneas over 6.5 hours of sleep give an AHI of about 15.7 events per hour.
What AHI is considered normal in adults?
Using standard adult criteria, an AHI below 5 events per hour is considered normal. An AHI of 5 to under 15 is mild sleep apnea, 15 to under 30 is moderate, and 30 or more is severe. Pediatric thresholds are lower, so these bands apply to adults.
What is the difference between AHI and RDI?
AHI counts only apneas and hypopneas per hour of sleep. The respiratory disturbance index (RDI) also includes respiratory effort-related arousals (RERAs), so RDI is always equal to or higher than AHI for the same sleep period.
Can this calculator diagnose sleep apnea?
No. It only divides event counts you already have, usually from a polysomnography or home sleep test, by your sleep time. Diagnosing sleep apnea requires a sleep study interpreted by a qualified clinician; use this result to understand your report, not to self-diagnose.

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