An apnea is a pause in breathing of at least 10 seconds; a hypopnea is a partial reduction in airflow with an oxygen drop or arousal. Sleep apnea causes snoring, daytime sleepiness and high blood pressure, and raises the risk of heart disease and car accidents.
How to use the AHI Calculator
- Apneas
- Hypopneas
- Respiratory effort-related arousals (RERAs)
- Oxygen desaturations (≥ 3%)
- Total sleep time
Results update as you type, and every field accepts the units shown in its menu.
How it works
Enter the counts from your sleep study or home test and your total sleep time. The calculator divides the events by the hours of sleep. Children use lower thresholds (AHI ≥ 1 is abnormal).
Tips
- Keep a regular wake-up time, even at weekends.
- Get daylight in the morning and dim screens in the hour before bed.
- Keep the bedroom cool, dark and quiet.
- See a doctor about loud snoring, gasping at night or strong daytime sleepiness.
Common mistakes to avoid
- Trying to catch up on a week of short nights in one lie-in.
- Using alcohol to fall asleep – it fragments sleep later in the night.
- Ignoring symptoms of sleep apnoea.
Inputs explained
| Field | What to enter |
|---|---|
| Apneas | A number |
| Hypopneas | A number |
| Respiratory effort-related arousals (RERAs) | A number |
| Oxygen desaturations (≥ 3%) | A number |
| Total sleep time | In h |
What each result means
- AHI = ([Apneas] + [Hypopneas])÷[Total sleep time]
- RDI = ([Apneas] + [Hypopneas] + [Respiratory effort-related arousals (RERAs)])÷[Total sleep time]
- Oxygen desaturation index = [Oxygen desaturations (≥ 3%)]÷[Total sleep time]
Example values
How the main result changes when Apneas changes and everything else stays at the example values above:
| Apneas | AHI (events/h) |
|---|---|
| 30 | 10.7 |
| 45 | 12.9 |
| 60 | 15 |
| 75 | 17.1 |
| 90 | 19.3 |
| 120 | 23.6 |
Health note: this calculator is for education and screening only and is not a diagnosis or treatment advice. Discuss your results with a qualified clinician.
Formula
AHI = (apneas + hypopneas) ÷ total sleep time (h)
RDI = (apneas + hypopneas + RERAs) ÷ total sleep time
ODI = desaturations ÷ total sleep time
Adults: < 5 normal · 5–14 mild · 15–29 moderate · ≥ 30 severe
Worked example
Inputs — Apneas: 60; Hypopneas: 45; Respiratory effort-related arousals (RERAs): 10; Oxygen desaturations (≥ 3%): 80; Total sleep time: 7 h.
Results — AHI = 15 events/h; RDI = 16.4 events/h; Oxygen desaturation index = 11.4 events/h.
Key terms
- Apnea
- Pause in breathing of 10 seconds or more.
- Hypopnea
- Partial reduction in breathing with an oxygen drop or arousal.
- RERA
- Respiratory effort-related arousal.
Frequently asked questions
What is a normal AHI?
Below 5 events per hour in adults and below 1 in children.
Is AHI the only thing that matters?
No – symptoms, oxygen levels and other conditions also guide treatment.
What treats sleep apnea?
CPAP, oral appliances, weight loss, positional therapy and sometimes surgery.