Blood Pressure Calculator

Per AHA 2017 guidelines, normal blood pressure is below 120 mmHg systolic AND below 80 mmHg diastolic. Readings of 120-129 systolic with diastolic below 80 are classified as Elevated. Stage 1 High Blood Pressure is 130-139 systolic or 80-89 diastolic. Stage 2 begins at 140/90. These thresholds apply to adults not on blood pressure medication.

Systolic pressure (the top number) is the force your blood exerts against artery walls when your heart beats and pumps blood. Diastolic pressure (the bottom number) is the pressure between heartbeats when your heart is filling with blood. Both numbers matter independently. You can have high blood pressure from either number alone meeting a threshold.

MAP is the average pressure in your arteries throughout one cardiac cycle. Formula: MAP = Diastolic + (Systolic - Diastolic) / 3. A MAP above 60 mmHg is generally needed to perfuse vital organs. Normal MAP is typically 70-100 mmHg. In intensive care, maintaining MAP above 65 mmHg is a key treatment target for shock and critical illness.

A hypertensive crisis is a systolic reading above 180 OR diastolic above 120. A hypertensive urgency has no symptoms; a hypertensive emergency includes chest pain, severe headache, shortness of breath, back pain, numbness, vision changes, or difficulty speaking. If you have any of those symptoms with a crisis-level reading, call 911 immediately. Without symptoms, contact your doctor or go to urgent care promptly.

Upper-arm validated digital monitors are accurate to within 5 mmHg when used correctly. Wrist monitors are less accurate due to position sensitivity. Look for devices validated by the British Hypertension Society (BHS), AAMI, or ESH. Proper cuff sizing is essential: a too-small cuff overestimates BP. Revalidate your device against a doctor's reading annually.

A difference of up to 10 mmHg between arms is common and normal. A consistent difference above 10-15 mmHg may indicate peripheral arterial disease or aortic coarctation and warrants medical evaluation. Use your higher-reading arm for ongoing monitoring, which is the AHA recommendation.

Pulse pressure is systolic minus diastolic pressure. A normal pulse pressure is 40-60 mmHg. A wide pulse pressure above 60 mmHg (common in older adults with arterial stiffness) is an independent predictor of cardiovascular risk. A narrow pulse pressure below 25 mmHg may indicate reduced cardiac output or aortic stenosis and should be evaluated medically.

Yes. Blood pressure follows a circadian pattern: it rises sharply in the morning, peaks in mid-afternoon, and dips during sleep. Morning surge is linked to higher rates of heart attack and stroke in the early hours. Nocturnal dipping (a 10-20% drop during sleep) is a healthy pattern; non-dippers and reverse-dippers have higher cardiovascular risk. Single readings do not capture this variation.

Sodium reduction (from 3,400 mg to 1,500 mg daily) can lower systolic BP by 4-8 mmHg. Aerobic exercise (30 minutes of moderate activity most days) reduces systolic by 4-9 mmHg. Losing 5 kg reduces systolic by roughly 4 mmHg. Limiting alcohol to 1-2 drinks per day and quitting smoking also have measurable effects. These lifestyle changes can sometimes eliminate the need for medication in Stage 1 hypertension.

Any reading above 180/120 mmHg. Also seek urgent care for any reading combined with symptoms: chest pain, shortness of breath, severe headache, visual disturbances, confusion, or weakness. Readings consistently above 160/100 even without symptoms warrant prompt medical evaluation, not just monitoring at home.

No. Blood pressure classification for children and adolescents is age, sex, and height dependent, using percentile charts rather than fixed thresholds. The AHA/ACC adult thresholds used here (Normal below 120/80, Stage 1 at 130/80) do not apply to children under 18. Pediatric BP evaluation should be done by a healthcare provider using age-appropriate normative data.