AHI Calculator
Calculate the Apnea-Hypopnea Index for sleep apnea.
Enter values to calculate your AHI.
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The Apnea-Hypopnea Index (AHI) is the primary metric used to diagnose and determine the severity of Obstructive Sleep Apnea (OSA). If you've undergone a sleep study (polysomnography), your report will include an AHI score. This AHI Calculator is designed to help you understand how that score is derived from the raw data of your sleep study, providing clarity on this crucial health indicator.
What is Sleep Apnea?
Sleep apnea is a common but serious sleep disorder where a person's breathing repeatedly stops and starts during sleep. The most common form is Obstructive Sleep Apnea (OSA), which occurs when the throat muscles relax and block the airway. These pauses in breathing can last from a few seconds to minutes and may occur 30 times or more in an hour. Each time breathing stops, the brain briefly rouses the person to reopen the airway. This severely disrupts the natural sleep architecture, preventing restorative deep sleep and leading to significant health consequences.
The Key Events: Apneas and Hypopneas
The AHI is calculated based on two types of respiratory events:
- Apnea: This is a complete cessation of airflow for at least 10 seconds. Essentially, you stop breathing entirely for a short period.
- Hypopnea: This is a partial blockage of the airway that results in a shallow breathing event, causing at least a 30% reduction in airflow for 10 seconds or more, accompanied by a drop in blood oxygen saturation.
A sleep study meticulously records every instance of apnea and hypopnea throughout the night.
How to Calculate the AHI
The formula for the Apnea-Hypopnea Index is simple but powerful:
AHI = (Total Number of Apneas + Total Number of Hypopneas) / Total Hours of Sleep
The result represents the average number of respiratory events you experience per hour of sleep. This single number is then used to classify the severity of sleep apnea.
Interpreting Your AHI Score
The severity of Obstructive Sleep Apnea in adults is categorized as follows:
| Severity Level | AHI Score (Events per Hour) |
|---|---|
| Normal | Fewer than 5 |
| Mild Sleep Apnea | 5 to 14 |
| Moderate Sleep Apnea | 15 to 29 |
| Severe Sleep Apnea | 30 or more |
This calculator provides a visual bar and a clear category label to help you instantly see where a result falls on this spectrum.
Why is Knowing Your AHI Important?
An elevated AHI is a serious health concern. The repeated drops in blood oxygen levels and the stress of constant waking put enormous strain on the cardiovascular system. Untreated sleep apnea is strongly linked to a host of health problems, including:
- High blood pressure (hypertension)
- Heart disease, including heart attack and atrial fibrillation
- Stroke
- Type 2 diabetes
- Daytime fatigue, which increases the risk of workplace and driving accidents
- Depression and cognitive impairment
Understanding your AHI is the first step toward seeking appropriate treatment. The primary treatment for moderate to severe OSA is Continuous Positive Airway Pressure (CPAP) therapy, which uses a machine to keep your airway open while you sleep. Other options may include oral appliances or lifestyle changes like weight loss.
Disclaimer: This calculator is for educational purposes only. The diagnosis and management of sleep apnea must be done by a qualified healthcare professional. If you suspect you have sleep apnea (symptoms include loud snoring, observed breathing pauses, and excessive daytime sleepiness), please consult a doctor or a sleep specialist.