Calculate your Apnea-Hypopnea Index from sleep study data. Includes supine AHI, REM AHI, positional analysis, and severity grading.
The AHI (Apnea-Hypopnea Index) Calculator computes your apnea-hypopnea index from sleep study data, providing severity classification, positional analysis (supine vs. non-supine), and REM-dependent analysis.
The AHI is the primary metric used to classify obstructive sleep apnea (OSA), the most common sleep-related breathing disorder affecting an estimated 936 million adults worldwide. It measures the number of complete airflow cessations (apneas) and partial reductions (hypopneas) per hour of sleep. Diagnosis still depends on the broader sleep-study and symptom context, not the number alone.
Beyond the overall AHI, this calculator provides subgroup analyses that can change how the sleep-study report is interpreted. Positional OSA (supine AHI ≥2× non-supine AHI), REM-dependent OSA, and the SpO₂ nadir all add context beyond the headline AHI. The page keeps those values grouped so the report can be reviewed more coherently.
Sleep study reports often include multiple event counts, oxygen values, and subgroup analyses that are difficult to compare at a glance. This calculator keeps the core AHI context together with positional and REM-specific breakdowns so the same report can be reviewed more consistently and interpreted without losing the main sleep-study structure. It is useful when you need a concise summary of the study rather than a page of separate numbers.
AHI = (Total Apneas + Total Hypopneas) / Total Sleep Time (hours) Apnea: Complete airflow cessation ≥10 seconds Hypopnea: ≥30% airflow reduction with ≥3% SpO₂ desaturation or arousal (AASM 2012) Supine AHI = Supine events / Supine time Positional OSA: Supine AHI ≥ 2× Non-supine AHI
Result: AHI = 15.0 events/hr — Moderate OSA
With 105 total events over 7 hours, the AHI is 15.0, placing this patient in the moderate OSA category. The SpO₂ nadir of 82% indicates moderate hypoxic burden. In practice, this kind of result usually leads to a fuller sleep-medicine review rather than relying on the AHI alone.
A polysomnography report contains far more than the AHI alone. Key metrics include sleep efficiency, sleep staging distribution, periodic limb movement index, central vs. obstructive event classification, and oxygen desaturation index. The AHI remains the primary severity summary, but it is only one part of the full sleep-study interpretation.
Untreated moderate-to-severe OSA is associated with a 2-3× increased risk of hypertension, 2-3× risk of atrial fibrillation, 1.5-2× risk of coronary artery disease, and 1.5-3× risk of stroke. The intermittent hypoxia–reoxygenation cycle causes oxidative stress, systemic inflammation, sympathetic activation, and endothelial dysfunction. Treatment with CPAP shows significant reduction in blood pressure and cardiovascular events.
Positional disease, REM-predominant disease, and deep oxygen desaturations can make two patients with the same overall AHI look clinically different. That is why this page keeps the subgroup values visible instead of reducing the report to one number.
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This page divides the total number of apneas and hypopneas by total sleep time to calculate AHI, then adds optional positional and REM-specific subgroup calculations when those inputs are available. It is built to summarize a sleep-study result, not to diagnose sleep apnea without the underlying study and symptom context.
The page keeps oxygen nadir, positional patterns, and REM patterns visible because the same overall AHI can have different clinical context depending on the rest of the sleep report. Treatment decisions still require clinician review of the full study.
AHI counts apneas and hypopneas per hour. RDI (Respiratory Disturbance Index) also includes RERAs (respiratory effort-related arousals), making it a more sensitive but less specific measure. AHI is the standard for OSA diagnosis.
CPAP is commonly part of the discussion for higher AHI bands, especially when symptoms, oxygen desaturation, or cardiometabolic comorbidity are present. The actual management plan still depends on the full sleep-study context and clinical history.
Home sleep tests (Type III) tend to underestimate AHI because they measure recording time rather than actual sleep time. A negative HSAT in a high-probability patient should be followed by in-lab PSG.
Positional OSA occurs when the supine AHI is at least twice the non-supine AHI. These patients may benefit from positional therapy (devices that prevent supine sleep) as standalone or adjunct treatment.
During REM sleep, skeletal muscle tone decreases (atonia), including pharyngeal dilator muscles, making the airway more collapsible. Some patients have OSA only during REM sleep.
Yes. Weight loss of 10-15% can reduce AHI by 50% in obese patients. Positional therapy, oral appliances, myofunctional therapy, and surgeries like UPPP or MMA can also reduce AHI.