STOP-BANG Calculator
Use our free Stopbangcalculator Calculator to get personalized health results. Based on validated medical formulas and clinical guidelines.
Calculator
Adjust values & calculateSTOP-BANG Questionnaire: Answer each question below. The acronym stands for Snoring, Tired, Observed, Pressure, BMI, Age, Neck, Gender.
Criteria Breakdown
Formula
Eight yes/no criteria: Snoring (loud), Tired (daytime fatigue), Observed apneas, blood Pressure (treated hypertension), BMI > 35, Age > 50, Neck > 40 cm, Gender (male). Score 0-2: Low risk, 3-4: Intermediate risk, 5-8: High risk for moderate-to-severe OSA.
Last reviewed: January 2026
Worked Examples
Example 1: High-Risk Preoperative Patient
Example 2: Low-Risk Female Patient
Background & Theory
The Stopbang 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 Stopbang 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-BANG Questionnaire: A Practical Approach to Screen for OSA (Chest, 2016)
- 2Chung F et al. - STOP Questionnaire: A Tool to Screen Patients for Obstructive Sleep Apnea (Anesthesiology, 2008)
- 3American Society of Anesthesiologists - Practice Guidelines for Perioperative Management of OSA
Formula
STOP-BANG Score = Sum of 8 binary criteria (0 or 1 each, max 8)
Eight yes/no criteria: Snoring (loud), Tired (daytime fatigue), Observed apneas, blood Pressure (treated hypertension), BMI > 35, Age > 50, Neck > 40 cm, Gender (male). Score 0-2: Low risk, 3-4: Intermediate risk, 5-8: High risk for moderate-to-severe OSA.
Worked Examples
Example 1: High-Risk Preoperative Patient
Problem: A 55-year-old male scheduled for knee surgery: loud snoring, daytime tiredness, wife observed apneas, on BP medication, BMI 38, neck 17 inches. Calculate STOP-BANG.
Solution: S - Snoring: YES (1)\nT - Tired: YES (1)\nO - Observed apneas: YES (1)\nP - Blood Pressure treatment: YES (1)\nB - BMI 38 > 35: YES (1)\nA - Age 55 > 50: YES (1)\nN - Neck 17 in = 43.2 cm > 40: YES (1)\nG - Male Gender: YES (1)\nTotal Score: 8/8
Result: STOP-BANG: 8/8 | High Risk for OSA | Sleep study before elective surgery recommended
Example 2: Low-Risk Female Patient
Problem: A 35-year-old female: no snoring, occasional tiredness, no observed apneas, normal BP, BMI 24, neck 13.5 inches. Calculate STOP-BANG.
Solution: S - Snoring: NO (0)\nT - Tired: NO (0)\nO - Observed apneas: NO (0)\nP - Blood Pressure: NO (0)\nB - BMI 24 <= 35: NO (0)\nA - Age 35 <= 50: NO (0)\nN - Neck 13.5 in = 34.3 cm <= 40: NO (0)\nG - Female Gender: NO (0)\nTotal Score: 0/8
Result: STOP-BANG: 0/8 | Low Risk for OSA | No further sleep evaluation needed
Frequently Asked Questions
What is the STOP-BANG questionnaire and what does it screen for?
The STOP-BANG questionnaire is a validated screening tool for obstructive sleep apnea (OSA) developed by Dr. Frances Chung at the University of Toronto in 2008. The acronym stands for eight binary (yes/no) risk factors: Snoring, Tiredness, Observed apneas, high blood Pressure, BMI over 35, Age over 50, Neck circumference over 40 cm, and male Gender. Each positive answer scores 1 point, for a total of 0 to 8. It was originally developed for preoperative screening of surgical patients but is now widely used in primary care and sleep medicine. The questionnaire takes less than 2 minutes to complete and has been validated in multiple languages and populations worldwide.
How are STOP-BANG scores interpreted for OSA risk?
STOP-BANG scores are categorized into three risk levels for moderate-to-severe obstructive sleep apnea. A score of 0 to 2 indicates low risk, with less than 10 percent probability of moderate-to-severe OSA. A score of 3 to 4 indicates intermediate risk, with approximately 25 to 35 percent probability. A score of 5 to 8 indicates high risk, with greater than 50 percent probability of moderate-to-severe OSA and greater than 70 percent probability of at least mild OSA. Additional high-risk criteria include a STOP score of 2 or more combined with either male gender, BMI over 35, or neck circumference over 40 cm. The sensitivity of STOP-BANG for moderate-to-severe OSA at a cutoff of 3 exceeds 90 percent.
Why is STOP-BANG used for preoperative screening?
Preoperative STOP-BANG screening is critical because undiagnosed obstructive sleep apnea significantly increases perioperative complications. Patients with undiagnosed OSA face a 2 to 4 times higher risk of postoperative respiratory complications including difficult intubation, oxygen desaturation, reintubation, and unplanned ICU admission. Sedatives, anesthetics, and opioid pain medications relax the upper airway and depress respiratory drive, worsening sleep apnea during and after surgery. The American Society of Anesthesiologists recommends preoperative OSA screening for all surgical patients. High-risk patients identified by STOP-BANG may benefit from preoperative CPAP therapy, modified anesthetic techniques, enhanced postoperative monitoring, and careful opioid management to reduce complications.
How accurate is the STOP-BANG questionnaire compared to other screening tools?
The STOP-BANG questionnaire has been extensively validated and demonstrates superior sensitivity compared to other OSA screening tools. For detecting moderate-to-severe OSA (AHI >= 15), STOP-BANG has a sensitivity of 90 to 100 percent at a cutoff score of 3, meaning it catches nearly all cases. Its specificity is lower (25 to 45 percent), meaning some people without OSA will screen positive. Compared to the Berlin Questionnaire (sensitivity 69 to 87 percent), STOP questionnaire alone (sensitivity 74 to 83 percent), and the Epworth Sleepiness Scale (sensitivity 27 to 66 percent), STOP-BANG consistently demonstrates the highest sensitivity. The trade-off of high sensitivity for lower specificity is appropriate for a screening tool because missing cases (false negatives) is more dangerous than over-referring for sleep studies.
What should I do if my STOP-BANG score indicates high risk?
A high-risk STOP-BANG score (5 or above) should prompt several important next steps. First, schedule an appointment with your primary care physician or directly with a sleep medicine specialist to discuss your results and symptoms. Your doctor will likely order a diagnostic sleep study, either an in-laboratory polysomnography or a home sleep apnea test, to confirm the diagnosis and determine severity. In the interim, avoid sleeping on your back (supine position), limit alcohol consumption especially before bedtime, and avoid sedative medications when possible. If diagnosed with OSA, treatment options include CPAP therapy, oral appliance therapy, weight loss, positional therapy, and in some cases surgical interventions. Do not delay evaluation, as untreated OSA significantly increases cardiovascular and accident risks.
Can the STOP-BANG questionnaire be used in children or adolescents?
The STOP-BANG questionnaire was developed and validated exclusively for adult populations and is not appropriate for use in children or adolescents under 18 years of age. Pediatric OSA has different risk factors, diagnostic thresholds, and underlying mechanisms compared to adult OSA. In children, the primary risk factor is adenotonsillar hypertrophy rather than obesity, and the AHI diagnostic threshold is 1 event per hour rather than 5. Pediatric screening tools include the Pediatric Sleep Questionnaire (PSQ) and the Sleep-Related Breathing Disorder scale of the Pediatric Sleep Questionnaire, both specifically validated for children. For adolescents transitioning to adult care, the STOP-BANG may become applicable at age 18, but clinicians should use clinical judgment when applying adult screening tools to older adolescents.
References
- Chung F et al. - STOP-BANG Questionnaire: A Practical Approach to Screen for OSA (Chest, 2016)
- Chung F et al. - STOP Questionnaire: A Tool to Screen Patients for Obstructive Sleep Apnea (Anesthesiology, 2008)
- American Society of Anesthesiologists - Practice Guidelines for Perioperative Management of OSA
Reviewed by Rahul Singh, Health & Wellness Specialist · Editorial policy