Blood pressure calculator
Enter your reading, see your blood pressure category.
What is a normal blood pressure?
Less than 120 systolic and less than 80 diastolic, by the American Heart Association chart.
What are the blood pressure categories?
Normal: under 120 and under 80. Elevated: 120–129 and under 80. Stage 1 hypertension: 130–139 or 80–89. Stage 2 hypertension: 140 or higher or 90 or higher. Severe hypertension: higher than 180 and/or higher than 120.
Which number decides the category?
Whichever is higher. 125/85 is stage 1 hypertension because the bottom number is in the 80–89 range.
What should I do with a very high reading?
The AHA says to wait at least a minute and measure again. If it stays above 180/120 and you have symptoms such as chest pain, shortness of breath, back pain, numbness, weakness, a change in vision or difficulty speaking, call 911; without symptoms, call your healthcare professional.
Does one reading mean I have high blood pressure?
No — a diagnosis is based on the average of several readings on different occasions. Talk with your doctor about your numbers.
What do the two numbers mean?
The top number, systolic, is the pressure in the arteries when the heart beats. The bottom number, diastolic, is the pressure between beats, when the heart relaxes. Both are in millimeters of mercury (mm Hg).
How should I measure at home?
The American Heart Association advises avoiding caffeine, exercise, smoking and food for 30 minutes beforehand and resting quietly for five minutes. Sit with your back supported, feet flat and your arm on a surface with the cuff at heart level, and take two readings one minute apart.
What is pulse pressure?
It is the top number minus the bottom number. For a reading of 128/84 it is 128 − 84 = 44 mm Hg. The categories on this page use only the two numbers themselves, not the difference.
How the categories work
The calculator compares your systolic and diastolic numbers with the American Heart Association chart and gives the highest category that either number reaches. Normal is below 120 and below 80. Elevated is 120 to 129 with a diastolic below 80. Stage 1 hypertension starts at 130 or 80, stage 2 at 140 or 90, and a reading above 180 or above 120 is severe. Because either number can set the category, a normal top number does not make a high bottom number normal.
Worked examples
118/76 mm Hg is normal; 124/78 mm Hg is elevated; 128/84 mm Hg is stage 1 hypertension; 136/92 mm Hg is stage 2 hypertension; 150/70 mm Hg is stage 2 hypertension; 185/100 mm Hg is severe hypertension.
In the fourth example (136/92) the top number alone would be stage 1, but the bottom number is 90 or more, so the category is stage 2. In the fifth (150/70) the bottom number is normal and the top number puts it in stage 2.
Common mistakes
- Judging from a single reading. Blood pressure changes from minute to minute. A diagnosis uses the average of several readings on different occasions, taken with correct technique.
- Measuring right after coffee, exercise or a stressful drive. This can push the numbers up. The AHA recommends resting for five minutes first.
- Using the wrong cuff size or arm position. A cuff that is too small, or an arm hanging below heart level, can give a falsely high number.
Sources and related calculators
Categories: the American Heart Association, "Understanding Blood Pressure Readings." Measurement method: the AHA scientific statement "Measurement of Blood Pressure in Humans" and the AHA and AMA joint policy statement on self-measured blood pressure monitoring at home. Related: mean arterial pressure calculator, BMI calculator and target heart rate calculator.
For general information only — not medical advice. Talk with your doctor or another health professional about your own health. How we check our calculators.