Blood Pressure Calculator

The top number, systolic, is the pressure in your arteries when your heart beats and pushes blood out. The bottom number, diastolic, is the pressure when your heart relaxes between beats. So a reading of 120/80 mmHg means a systolic pressure of 120 and a diastolic pressure of 80. Both numbers matter — a high systolic reading and a high diastolic reading are each linked to cardiovascular risk on their own.

This calculator uses the 2017 American College of Cardiology / American Heart Association categories: under 120/80 is Normal, 120-129 with diastolic under 80 is Elevated, 130-139 or 80-89 is Stage 1 hypertension, and 140/90 or above is Stage 2. It's worth knowing these aren't universal — the World Health Organization, European guidelines, and the UK's NICE all set the hypertension line at 140/90 instead of 130/80, so the same reading can be labeled differently depending on which guideline you're comparing to.

Not on its own. Blood pressure naturally shifts throughout the day with stress, activity, caffeine, and even how you're sitting, and clinic readings in particular can run high just from the anxiety of being measured (sometimes called white-coat hypertension). A real diagnosis needs multiple readings, often on different days, following proper technique — sitting quietly for 5 minutes first, feet flat, arm supported at heart level. If a home reading concerns you, retest calmly a few minutes later and track a pattern rather than reacting to one number.

MAP estimates the average pressure pushing blood through your body over a full heartbeat cycle, calculated as (2 x diastolic + systolic) divided by 3; a typical healthy range is roughly 70 to 105 mmHg. Pulse pressure is simply systolic minus diastolic, typically 40 to 60 mmHg; a notably wide gap can be a sign of stiffening arteries, especially in older adults. Both add context beyond the two headline numbers, though neither replaces a full evaluation from your doctor.

A reading of 180/120 mmHg or higher is considered a hypertensive crisis. If you get a reading that high, sit down and re-check it after five minutes of calm rest — but if it's still that high, or if you have chest pain, trouble breathing, severe headache, weakness, difficulty speaking, or vision changes at any point, treat it as an emergency and seek immediate medical care rather than waiting for a routine appointment.