Cardiac Output Calculator

Cardiac output is the volume of blood pumped by the heart each minute. It links heart rate, the number of beats per minute, with stroke volume, the amount ejected during each beat. Adequate output is necessary to deliver oxygen and nutrients to tissues and remove metabolic waste. Clinicians interpret it together with blood pressure, oxygenation, vascular resistance, symptoms, and organ function rather than treating it as an isolated target. The most direct calculation in this tool multiplies heart rate by stroke volume. Because stroke volume is commonly entered in milliliters, the product is divided by 1,000 to report liters per minute. For example, 72 beats per minute and 70 mL per beat produce 5.04 L/min. This arithmetic can be used with stroke volume obtained from echocardiography, thermodilution, or another validated technique. The Fick principle estimates flow from whole-body oxygen consumption divided by the difference between arterial and mixed venous oxygen content. This calculator expects oxygen consumption in mL/min and the oxygen difference in mL/L, which directly yields L/min. The method depends on representative blood samples and an accurate oxygen-consumption value. Estimated rather than measured consumption can introduce substantial error in some patients. The echocardiography mode accepts heart rate and a stroke volume already expressed in liters per beat. In clinical echocardiography, stroke volume is often derived from the left ventricular outflow tract area multiplied by its velocity-time integral. Small errors in measuring outflow tract diameter can be magnified because diameter is squared when area is calculated. Consistent technique is therefore essential when comparing serial results. Resting adult cardiac output is often around 4 to 8 L/min, but normal physiology varies with body size, exercise, pregnancy, fever, anemia, medication, and many disease states. A result outside this broad interval is not automatically abnormal, and a result inside it does not rule out cardiovascular illness. Cardiac index may be more suitable when comparing people of different sizes because it normalizes output to body surface area. This calculator provides transparent arithmetic for education and checking measurements. It does not replace calibrated equipment, clinical judgment, or specialist evaluation. Unexpected values should prompt review of units, sampling, timing, and measurement quality before conclusions are drawn. People with chest pain, severe shortness of breath, fainting, confusion, or signs of poor circulation need urgent medical evaluation.