Stop Bang Score Calculator
Screen for obstructive sleep apnea risk using the STOP-BANG questionnaire. Enter values for instant results with step-by-step formulas.
Calculator
Adjust values & calculateSTOP - Symptom Questions
BANG - Risk Factor Questions
Interpretation
A STOP-BANG score of 0-2 indicates low risk for obstructive sleep apnea. The negative predictive value at this threshold is approximately 90 percent for moderate-to-severe OSA.
Recommendation
No urgent sleep study indicated based on this screening. Consider reassessment if new symptoms develop or risk factors change.
Formula
Eight yes/no questions scored 0-1 each. STOP = Snoring, Tiredness, Observed apnea, blood Pressure. BANG = BMI>35, Age>50, Neck>40cm, Gender (male). Score 0-2 = Low risk, 3-4 = Intermediate risk, 5-8 = High risk for OSA.
Last reviewed: January 2026
Worked Examples
Example 1: Preoperative Patient with High Risk
Example 2: Low Risk Screening Patient
Background & Theory
The Stop-Bang Score Calculator applies the following established principles and formulas. Health and medicine calculators are grounded in validated physiological measurement methods established through decades of clinical research. Body Mass Index, or BMI, is calculated by dividing weight in kilograms by height in meters squared (kg/m²), a formula originating from Adolphe Quetelet's 19th-century statistical work and later codified by the WHO into standard classifications: underweight below 18.5, normal weight 18.5 to 24.9, overweight 25 to 29.9, and obese at 30 and above. Basal Metabolic Rate quantifies the minimum energy required to sustain life at rest. The Mifflin-St Jeor equation, published in 1990 and widely regarded as the most accurate for most adults, calculates BMR as (10 × weight in kg) + (6.25 × height in cm) − (5 × age) ± sex adjustment. The older Harris-Benedict equations, revised in 1984 by Roza and Shizgal, remain in common use. Total Daily Energy Expenditure is derived by multiplying BMR by a physical activity factor ranging from 1.2 for sedentary individuals to 1.9 for extremely active ones, following the methodology validated by doubly labeled water studies. Body fat percentage can be estimated without laboratory equipment using the U.S. Navy circumference method, which uses neck, waist, and hip measurements, or via BMI-derived equations adjusted for age and sex. The Jackson-Pollock skinfold method offers higher precision with calipers. Blood pressure classification, according to the American College of Cardiology and the 2017 ACC/AHA guidelines, defines normal as below 120/80 mmHg, elevated as 120 to 129 systolic, and hypertension stage 1 as 130 to 139 systolic or 80 to 89 diastolic. Target heart rate zones for aerobic exercise are derived from maximum heart rate estimates, most commonly using the formula 220 minus age in years, with moderate-intensity training typically defined as 50 to 70 percent of maximum heart rate and vigorous intensity at 70 to 85 percent, consistent with CDC and American Heart Association guidelines. These thresholds guide safe and effective cardiovascular conditioning.
History
The history behind the Stop-Bang Score Calculator traces back through the following developments. The history of health measurement stretches back to ancient Greece, where Hippocrates around 400 BCE laid the foundation for observational medicine by systematically recording patient symptoms, diet, and environment. His humoral theory, though scientifically superseded, established the principle that the body operates as an interconnected system subject to measurable imbalance. The transformation toward modern medicine accelerated in the 19th century. Louis Pasteur and Robert Koch developed germ theory in the 1860s and 1870s, identifying microorganisms as disease agents and enabling targeted interventions. Florence Nightingale, working during the Crimean War in the 1850s, introduced statistical analysis to nursing practice, demonstrating through data visualization that sanitation reduced mortality. Her work is foundational to evidence-based health measurement. The discovery of vitamins in the early 20th century, beginning with Casimir Funk's coinage of the term in 1912 and culminating in the isolation of vitamins A through K, created the field of nutritional science and gave rise to dietary reference intake frameworks. The World Health Organization, founded in 1948, subsequently established global standards for health metrics, disease classification through the International Classification of Diseases, and recommended daily allowances. The BMI as a clinical screening tool gained traction in the 1970s through Ancel Keys' large-scale epidemiological work, which validated Quetelet's index as a population-level obesity indicator. Through the 1980s and 1990s, the Framingham Heart Study produced landmark data linking cholesterol, blood pressure, and lifestyle factors to cardiovascular disease risk, directly shaping the numeric thresholds still used in health calculators. The evidence-based medicine movement, formalized by Gordon Guyatt and colleagues at McMaster University in the early 1990s, demanded that all health recommendations derive from systematically graded clinical evidence. The digital health era beginning in the 2000s brought these formulas to consumer devices, wearable sensors, and smartphone applications, expanding access to health self-monitoring on a global scale and enabling population-level data collection that continues to refine clinical reference ranges.
Frequently Asked Questions
Sources & References
- 1Chung F, et al. STOP Questionnaire: A Tool to Screen Patients for Obstructive Sleep Apnea. Anesthesiology. 2008;108(5):812-821
- 2Chung F, et al. High STOP-Bang score indicates a high probability of obstructive sleep apnoea. Br J Anaesth. 2012;108(5):768-775
- 3American Academy of Sleep Medicine - Clinical Practice Guidelines
Formula
STOP-BANG Score = S + T + O + P + B + A + N + G (each 0 or 1, total 0-8)
Eight yes/no questions scored 0-1 each. STOP = Snoring, Tiredness, Observed apnea, blood Pressure. BANG = BMI>35, Age>50, Neck>40cm, Gender (male). Score 0-2 = Low risk, 3-4 = Intermediate risk, 5-8 = High risk for OSA.
Worked Examples
Example 1: Preoperative Patient with High Risk
Problem: A 55-year-old male patient scheduled for knee surgery reports loud snoring, daytime tiredness, and his wife has observed him stop breathing during sleep. He has treated hypertension, BMI of 38, and neck circumference of 43 cm.
Solution: STOP-BANG Score:\nS (Snoring) = Yes (1)\nT (Tired) = Yes (1)\nO (Observed) = Yes (1)\nP (Pressure) = Yes (1)\nB (BMI > 35) = Yes (1)\nA (Age > 50) = Yes (1)\nN (Neck > 40cm) = Yes (1)\nG (Male) = Yes (1)\nTotal = 8/8
Result: STOP-BANG Score: 8/8 (High Risk) - Very high probability of severe OSA. Polysomnography and anesthesiology consultation essential before surgery.
Example 2: Low Risk Screening Patient
Problem: A 35-year-old female patient presents for routine health screening. She does not snore, has no daytime sleepiness, no observed apneas, normal blood pressure, BMI of 24, and neck circumference of 34 cm.
Solution: STOP-BANG Score:\nS (Snoring) = No (0)\nT (Tired) = No (0)\nO (Observed) = No (0)\nP (Pressure) = No (0)\nB (BMI > 35) = No (0)\nA (Age > 50) = No (0)\nN (Neck > 40cm) = No (0)\nG (Male) = No (0)\nTotal = 0/8
Result: STOP-BANG Score: 0/8 (Low Risk) - Very low probability of OSA. No sleep study indicated at this time.
Frequently Asked Questions
What is the STOP-BANG questionnaire and what does it screen for?
The STOP-BANG questionnaire is an eight-item screening tool designed to identify patients at risk for obstructive sleep apnea (OSA). Developed by Dr. Frances Chung and colleagues at the University of Toronto in 2008, it was originally created for preoperative screening but has since been widely adopted in primary care and other clinical settings. The acronym represents eight risk factors: Snoring, Tiredness, Observed apnea, blood Pressure, BMI, Age, Neck circumference, and Gender. Each item is scored as yes (1 point) or no (0 points), yielding a total score of 0 to 8. The questionnaire takes less than two minutes to complete and requires no special equipment or training.
How are STOP-BANG scores interpreted for OSA risk stratification?
STOP-BANG scores categorize patients into three risk groups for obstructive sleep apnea. A score of 0 to 2 indicates low risk, with a high negative predictive value of approximately 90 percent for moderate-to-severe OSA. A score of 3 to 4 indicates intermediate risk, where further clinical evaluation and possible sleep testing may be warranted. A score of 5 to 8 indicates high risk, with strong predictive value for moderate-to-severe OSA. Studies have shown that higher scores correlate with greater OSA severity, with scores of 7 to 8 having very high probability of severe OSA (AHI greater than 30). The simple scoring makes it practical for rapid clinical decision-making in various healthcare settings.
Why is BMI greater than 35 specifically chosen as the cutoff in STOP-BANG?
A BMI greater than 35 kg/m2 was selected as the STOP-BANG threshold because it represents Class II obesity, which is associated with substantially increased risk of obstructive sleep apnea. Excess adipose tissue in the upper airway region, including the tongue, soft palate, and lateral pharyngeal walls, narrows the airway and increases collapsibility during sleep. Studies have demonstrated that the prevalence of OSA increases progressively with BMI, with approximately 70 to 80 percent of morbidly obese patients having some degree of OSA. The relationship between obesity and OSA is bidirectional, as untreated OSA can promote weight gain through metabolic dysregulation, sleep fragmentation, and decreased physical activity. Weight loss of 10 to 15 percent can significantly reduce OSA severity.
How does the STOP-BANG compare to other sleep apnea screening tools?
The STOP-BANG questionnaire has been compared extensively to other OSA screening tools including the Berlin Questionnaire, Epworth Sleepiness Scale, and the STOP questionnaire (the first four items only). Multiple systematic reviews have found that the STOP-BANG has the highest sensitivity among available screening tools, ranging from 83 to 100 percent for moderate-to-severe OSA at the cutoff of 3 or higher. However, its specificity is relatively lower, ranging from 37 to 56 percent, meaning it produces more false positives than some alternatives. The Berlin Questionnaire may have higher specificity but lower sensitivity and takes longer to administer. The STOP-BANG strikes the best balance between simplicity, speed, and sensitivity for a screening tool in clinical practice.
Why is the STOP-BANG particularly important for preoperative screening?
Preoperative screening for OSA using the STOP-BANG is critical because undiagnosed OSA significantly increases perioperative risk. Patients with untreated OSA are at higher risk for difficult intubation, postoperative respiratory complications, cardiac arrhythmias, and intensive care unit admission. General anesthesia and opioid analgesics further compromise upper airway patency in OSA patients, increasing the risk of postoperative airway obstruction and oxygen desaturation. The American Society of Anesthesiologists guidelines recommend screening surgical patients for OSA, and the STOP-BANG is specifically endorsed for this purpose. Identifying high-risk patients preoperatively allows anesthesiologists to plan appropriate airway management, monitoring, and postoperative care strategies.
What is the difference between the STOP portion and the BANG portion of the questionnaire?
The STOP and BANG portions capture different types of risk information for obstructive sleep apnea. The STOP portion (Snoring, Tiredness, Observed apnea, blood Pressure) consists of symptom-based and clinical history questions that reflect current manifestations of possible OSA. These are subjective or clinically identified signs that suggest the presence of sleep-disordered breathing. The BANG portion (BMI, Age, Neck circumference, Gender) consists of demographic and anthropometric risk factors that are objective and easily measured. When used alone, the STOP questions have moderate sensitivity and specificity. Adding the BANG criteria significantly improves the sensitivity of the tool, particularly for detecting moderate-to-severe OSA, at the cost of somewhat reduced specificity.
References
- Chung F, et al. STOP Questionnaire: A Tool to Screen Patients for Obstructive Sleep Apnea. Anesthesiology. 2008;108(5):812-821
- Chung F, et al. High STOP-Bang score indicates a high probability of obstructive sleep apnoea. Br J Anaesth. 2012;108(5):768-775
- American Academy of Sleep Medicine - Clinical Practice Guidelines
Reviewed by Rahul Singh, Health & Wellness Specialist · Editorial policy