Qsofa Score Calculator
Screen for sepsis outside the ICU using the quick SOFA bedside criteria. Enter values for instant results with step-by-step formulas.
Calculator
Adjust values & calculate1 point if 100 mmHg or below
1 point if 22 breaths/min or above
1 point if less than 15 (any altered mentation)
No qSOFA criteria met. Low probability of sepsis based on bedside assessment alone. Continue standard monitoring and reassess as clinically indicated.
In-hospital mortality approximately 3-5%
Formula
Each of the three criteria scores 1 point if met: systolic blood pressure 100 mmHg or below, respiratory rate 22 or above, and Glasgow Coma Scale less than 15. A total score of 2 or more is a positive screen for sepsis risk.
Last reviewed: January 2026
Worked Examples
Example 1: Emergency Department Screening
Example 2: General Ward Assessment
Background & Theory
The Qsofa 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 Qsofa 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
Formula
qSOFA = (SBP<=100) + (RR>=22) + (GCS<15)
Each of the three criteria scores 1 point if met: systolic blood pressure 100 mmHg or below, respiratory rate 22 or above, and Glasgow Coma Scale less than 15. A total score of 2 or more is a positive screen for sepsis risk.
Worked Examples
Example 1: Emergency Department Screening
Problem: A 72-year-old patient presents with suspected urinary tract infection. Vitals: BP 88/52 mmHg, RR 26 breaths/min, GCS 14 (slightly confused). Calculate the qSOFA score.
Solution: Systolic BP = 88 mmHg (<=100): 1 point\nRespiratory Rate = 26 breaths/min (>=22): 1 point\nGCS = 14 (<15): 1 point\nTotal qSOFA = 3/3
Result: qSOFA Score: 3 (High Risk) — Immediate sepsis workup, blood cultures, IV antibiotics, and ICU consultation recommended
Example 2: General Ward Assessment
Problem: A 55-year-old post-surgical patient develops fever. Vitals: BP 118/76 mmHg, RR 20 breaths/min, GCS 15 (alert). Calculate the qSOFA score.
Solution: Systolic BP = 118 mmHg (>100): 0 points\nRespiratory Rate = 20 breaths/min (<22): 0 points\nGCS = 15 (=15): 0 points\nTotal qSOFA = 0/3
Result: qSOFA Score: 0 (Low Risk) — Continue standard monitoring; qSOFA does not rule out infection, consider clinical context
Frequently Asked Questions
What is the qSOFA score and when should it be used?
The quick Sequential Organ Failure Assessment (qSOFA) score is a bedside screening tool introduced as part of the Sepsis-3 consensus definitions in 2016. It is designed to identify patients outside the intensive care unit who are at risk for poor outcomes due to suspected infection. Unlike the full SOFA score, qSOFA requires no laboratory tests and can be calculated rapidly at the bedside using only three clinical parameters: systolic blood pressure, respiratory rate, and altered mental status assessed by the Glasgow Coma Scale. A score of two or more points suggests the patient may have sepsis and warrants further clinical investigation including blood cultures, lactate measurement, and consideration of early antibiotic therapy and fluid resuscitation.
How is the qSOFA score calculated and what are the criteria?
The qSOFA score ranges from 0 to 3 and assigns one point for each of the following criteria that is met: systolic blood pressure of 100 mmHg or less, respiratory rate of 22 breaths per minute or greater, and altered mental status defined as a Glasgow Coma Scale score below 15. Each criterion receives exactly one point, with no partial scoring or weighting. The score is considered positive for sepsis screening when two or more points are present. The simplicity of this scoring system is intentional, as it enables rapid assessment by any healthcare provider including nurses, paramedics, and physicians without requiring laboratory results or complex calculations. This makes it particularly valuable in emergency departments, general wards, and prehospital settings.
What is the sensitivity and specificity of the qSOFA score?
The qSOFA score has moderate specificity but relatively low sensitivity for predicting sepsis-related outcomes. Studies show a specificity of approximately 80-90 percent but sensitivity of only around 50-60 percent for in-hospital mortality. This means that while a positive qSOFA score (two or more) reliably identifies high-risk patients, a negative score does not rule out sepsis. Because of this limitation, the Surviving Sepsis Campaign 2021 guidelines recommend against using qSOFA as the sole screening tool for sepsis and suggest combining it with other clinical assessments and biomarkers such as procalcitonin and serum lactate levels. The qSOFA performs best as a prognostic tool rather than a diagnostic tool for identifying patients requiring escalated care.
How does qSOFA differ from the full SOFA score?
The full SOFA score evaluates six organ systems using both clinical and laboratory parameters: respiratory function via PaO2/FiO2 ratio, coagulation via platelet count, liver function via bilirubin level, cardiovascular function via mean arterial pressure and vasopressor requirements, central nervous system via Glasgow Coma Scale, and renal function via creatinine and urine output. Each system is scored from 0 to 4 for a maximum of 24 points. In contrast, qSOFA uses only three bedside parameters requiring no laboratory tests, making it much faster to calculate but less comprehensive. The full SOFA score is preferred for patients already in the ICU, while qSOFA serves as a rapid triage tool for patients on general wards or in emergency departments to prompt further evaluation.
Should clinical decisions be based solely on the qSOFA score?
No, clinical decisions should never rely exclusively on the qSOFA score. The tool is intended as a screening prompt to identify patients who may benefit from further sepsis workup, not as a standalone diagnostic criterion. A patient with a qSOFA score of zero or one may still have sepsis, particularly in early stages when vital signs have not yet deteriorated significantly. Conversely, elevated qSOFA criteria can occur in many non-sepsis conditions including heart failure, pulmonary embolism, stroke, and medication effects. Clinicians should integrate qSOFA results with complete clinical assessment, patient history, physical examination findings, and appropriate laboratory and imaging studies. Early lactate measurement and blood cultures remain essential components of the sepsis evaluation pathway regardless of the qSOFA result.
Does Qsofa Score Calculator work offline?
Once the page is loaded, the calculation logic runs entirely in your browser. If you have already opened the page, most calculators will continue to work even if your internet connection is lost, since no server requests are needed for computation.
References
Reviewed by Rahul Singh, Health & Wellness Specialist · Editorial policy