Blood Pressure Calculator

Blood pressure describes the force exerted by circulating blood against artery walls. A reading contains two numbers measured in millimeters of mercury. Systolic pressure, the upper number, represents pressure while the heart contracts. Diastolic pressure, the lower number, represents pressure while the heart relaxes between beats. This calculator compares both values with widely used adult categories and also derives mean arterial pressure and pulse pressure. The classification follows common American adult thresholds. A reading is normal when systolic pressure is below 120 and diastolic pressure is below 80. Elevated pressure has a systolic value from 120 through 129 while diastolic remains below 80. Stage 1 hypertension begins when systolic is 130 through 139 or diastolic is 80 through 89. Stage 2 begins at systolic 140 or diastolic 90. A systolic reading of 180 or higher, or diastolic of 120 or higher, falls in a crisis range that requires prompt professional guidance, especially when symptoms are present. Mean arterial pressure estimates the average arterial pressure during one cardiac cycle. At ordinary resting heart rates it is approximated as diastolic pressure plus one third of pulse pressure, which is equivalent to systolic plus twice diastolic divided by three. Pulse pressure is simply systolic minus diastolic. Clinicians interpret these derived values in context; neither replaces direct evaluation, repeated measurements, symptoms, or medical history. For a useful home reading, avoid caffeine, exercise, and smoking for about thirty minutes beforehand. Sit quietly with back supported, feet flat, legs uncrossed, and the cuffed arm supported near heart level. Use a validated monitor with the correct cuff size. Take two readings about one minute apart and record them. Blood pressure naturally varies with stress, activity, sleep, medicines, and time of day, so a trend is more informative than one isolated result. This calculator is educational and does not diagnose hypertension. Pregnancy, childhood, cardiovascular disease, and other clinical circumstances can require different interpretation. If readings are repeatedly high or unexpectedly low, discuss them with a qualified healthcare professional. Seek urgent care for crisis-range readings accompanied by chest pain, shortness of breath, weakness, confusion, vision change, or other concerning symptoms.