AHI Calculator - Index Score and Severity Band

The AHI calculator turns the apnea episodes, hypopnea episodes, and actual sleep time from a sleep study into an AHI score in events per hour, then labels that score with an adult severity band. The apnea hypopnea index is the standard score used to diagnose obstructive sleep apnea.

• • Reading a diagnostic sleep study: Enter apnea, hypopnea, and sleep time from a polysomnography or home sleep apnea test to get an AHI score and severity band.
• • Checking an on-CPAP report card: Switch to CPAP therapy report to add a therapy-status line that flags an AHI of 5 or higher.
• • Tracking RDI alongside AHI: Add the optional RERA count to surface the Respiratory Disturbance Index, used in place of AHI by some clinicians.
• • Comparing two study nights: Run the numbers for a baseline night and a follow-up night to see how the AHI changes after weight loss or a new device setting.

Most adults encounter AHI only after a clinician orders a sleep study, so the calculator is built around the values a real report shows: apnea events, hypopnea events, and actual sleep time in minutes.

For a related sleep planning view that works in cycle counts and minutes, Sleep Cycle Calculator pairs the AHI score with a bedtime and wake-time schedule.

The AHI calculator applies the standard AHI formula in three steps: it adds the apnea and hypopnea events, divides by the actual sleep time in minutes, and multiplies by 60 to scale the rate to one hour. The same arithmetic is used for diagnostic studies and on-CPAP report cards, with the report type only changing the therapy-status label.

• apneaEpisodes: Count of apnea events from the sleep study or CPAP report.
• hypopneaEpisodes: Count of hypopnea events from the same report.
• sleepTimeMinutes: Total minutes of actual sleep, not time in bed.
• reraEpisodes: Optional RERA count used to compute RDI alongside AHI.
• contextMode: Diagnostic or CPAP report card, used only to label the therapy-status line.

The result panel shows total events, sleep time, the AHI score, and the severity band together. When RERA is entered, an RDI row appears below the AHI.

According to Sleep journal (Malhotra et al., 2021), the AHI is the most studied metric of obstructive sleep apnea severity, with 0 to 4 events per hour considered normal, 5 to 14 mild, 15 to 29 moderate, and 30 or more severe

When the focus shifts to how REM minutes are distributed across a night, REM Sleep Calculator estimates the REM share using cycle counts and cycle length.

Four concepts keep the AHI score from being read as a personal verdict, and they explain why two people with the same AHI can feel very different the next day.

The AHI score is a rate, not a count, so the sleep time input matters as much as the event inputs.

A sleep specialist will usually quote the AHI unless the report card uses RDI directly, so the calculator keeps both visible.

To see how total sleep time fits into a recommended nightly range for the reader's age group, Sleep Calculator turns hours of sleep into a daily and weekly picture.

The form follows the same order as a real sleep study report, so the top field down keeps the arithmetic consistent with the scored report.

1. 1 Find the apnea and hypopnea counts on the report: Open the polysomnography summary or home sleep apnea test PDF and locate the totals for apnea events and hypopnea events.
2. 2 Enter the apnea and hypopnea episode counts: Type the apnea count into Apnea Episodes and the hypopnea count into Hypopnea Episodes, rounded to whole events.
3. 3 Enter the actual sleep time in minutes: Locate the Total Sleep Time line. The AHI calculator expects minutes, so 7 hours is 420 minutes. Do not enter time in bed.
4. 4 Add RERA only if the report lists it: If the report shows a respiratory effort-related arousal count, enter it in the optional RERA Episodes field to surface RDI alongside AHI.
5. 5 Pick the right report type: Choose Diagnostic for a baseline or titration study. Choose CPAP therapy report to add a therapy-status line that flags AHI of 5 or higher.
6. 6 Read the result and the severity band together: Use the severity band as the talking point with a clinician rather than the raw score alone.

A reader with a 7-hour home sleep apnea test that lists 12 apneas and 28 hypopneas enters 12, 28, and 420, leaves RERA at 0, and keeps Diagnostic. The result reads AHI 5.71 events per hour, severity band Mild.

When a reader wants to see how several short sleep nights add up against an age-based target, Sleep Debt Calculator turns nightly hours into a weekly shortfall.

Running the score by hand takes a minute of arithmetic, but the calculator adds labels and notes that a paper calculation does not show.

• • Adult severity band built in: The AHI score is paired with the AASM adult Normal, Mild, Moderate, and Severe bands, so the reader sees a label they can quote back to a clinician.
• • Sleep time in hours: The same panel reports the actual sleep time in hours next to the events-per-hour score, so the divisor is visible.
• • Optional RDI alongside AHI: A RERA field is included for readers whose report lists respiratory effort-related arousals, and the RDI row is shown next to the AHI.
• • CPAP therapy status note: When the report type is set to CPAP, the calculator adds a therapy-status line that flags an AHI of 5 or higher as therapy not yet on target, based on the AASM practice standard.
• • Rounding you can read aloud: AHI and RDI are rounded to two decimals and total events are kept as whole numbers, which mirrors the way a real report is quoted in clinic notes.
• • Reusable across studies: The same form works for a baseline diagnostic study, a split-night titration, an on-CPAP report card, and a follow-up study.

AHI is also a useful metric for tracking changes between studies, so the same form can be reused on a baseline night, a follow-up night, and an on-CPAP report.

The CPAP therapy-status line is a quick reading aid for a number often buried at the bottom of a printed report, not a replacement for a clinician's review.

To put the AHI score in context with a daytime sleepiness check, Epworth Sleepiness Scale Calculator scores how often sleepiness shows up across common daily activities.

Five factors can move an AHI score by enough to cross a severity band, so knowing them helps a reader understand why a number changes between studies.

• • AHI is the most studied metric of obstructive sleep apnea severity, but it does not capture event duration, oxygen desaturation depth, or arousal intensity, so two people with the same AHI can have very different symptoms.
• • Home sleep apnea tests can underestimate the AHI because they do not always record EEG and may miss events clearest on a full polysomnogram.

The severity band is the same for every adult reader, but the symptom load behind the score is not. A low AHI on a quiet night can still come with daytime sleepiness, and a high AHI on a fragmented night can come with surprisingly few daytime symptoms.

The rest of the interpretation belongs in a clinic visit, where the AHI is paired with the Epworth Sleepiness Scale and a review of the raw study tracing.

According to NHLBI, sleep apnea is diagnosed with a sleep study, and untreated sleep apnea can lead to serious problems such as stroke, heart attack, and difficulty concentrating

According to American Academy of Sleep Medicine, an on-CPAP AHI above 5 events per hour indicates the therapy is not yet working as it should

For a planning view that organizes a night into 90-minute cycle blocks, 90 Minute Sleep Cycle estimates bedtimes or wake times that land at the end of a complete cycle.