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Blood Pressure Calculator

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Enter your systolic and diastolic blood pressure readings to check your category and pulse pressure, based on American Heart Association / American College of Cardiology guidelines.

Blood Pressure Calculator

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Category
Normal
Pulse pressure
42 mmHg (Normal)
Based on a single reading. Diagnosis requires the average of two or more readings on separate visits - this is not a substitute for professional medical advice.

The classification

Normal: systolic under 120 AND diastolic under 80 Elevated: systolic 120-129 AND diastolic under 80 Stage 1 High: systolic 130-139 OR diastolic 80-89 Stage 2 High: systolic 140+ OR diastolic 90+ Hypertensive Crisis: systolic over 180 OR diastolic over 120 (seek care immediately) Low (Hypotension): systolic under 90 OR diastolic under 60 Pulse pressure = Systolic - Diastolic Under 40 mmHg: Low (Narrow) - 40-60 mmHg: Normal - Over 60 mmHg: High (Wide)
Example

A reading of 135/78: the systolic number (135) falls in the Stage 1 range even though the diastolic number (78) is still normal - either number crossing a threshold determines the category. Pulse pressure here is 135-78 = 57 mmHg, still within the normal 40-60 range.

Step-by-step guide

  1. Sit quietly for 5 minutes before measuring, with your back supported and feet flat on the floor - activity, caffeine, and a full bladder can all temporarily raise readings.
  2. Enter your systolic (top) and diastolic (bottom) numbers exactly as shown on your monitor.
  3. Read your category and pulse pressure - if your category is elevated or higher, consider a second reading a few minutes later.

What pulse pressure adds beyond the category

Pulse pressure - the gap between your two numbers - reflects how much your artery pressure swings with each heartbeat. A narrow pulse pressure can suggest the heart isn't pumping much blood per beat, while a wide pulse pressure (common with stiffer arteries in older adults) is linked to higher cardiovascular risk independent of the standard category. Two people can share the same "Stage 1" category with very different pulse pressures - 130/85 (pulse pressure 45) and 150/105 isn't Stage 1 at all, but 135/95 (pulse pressure 40) versus 135/65 (pulse pressure 70) shows how differently two Stage-1-adjacent readings can behave.

Common mistakes

Using a single reading as a diagnosis - blood pressure varies throughout the day, and clinical diagnosis is based on the average of multiple readings taken on separate occasions.
Measuring right after caffeine, exercise, or a stressful moment - all of these temporarily raise blood pressure, sometimes enough to shift the category.

Frequently asked questions

Which number matters more, systolic or diastolic?

Neither takes priority - your category is set by whichever number falls into the higher-risk range. A high systolic reading with a normal diastolic reading (or vice versa) still places you in that higher category.

What is pulse pressure and why does it matter?

Pulse pressure is the difference between your systolic and diastolic numbers. A healthy range is roughly 40-60 mmHg - a pulse pressure consistently above 60 mmHg is an independent risk factor for heart disease, particularly in older adults, regardless of your overall category.

What should I do if I get a hypertensive crisis reading?

Sit quietly for five minutes and retake the reading. If it's still that high, contact a healthcare professional right away - and if you have symptoms like chest pain, shortness of breath, or vision changes, seek emergency care immediately.

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