Heart & circulation
Blood pressure chart & category calculator
Enter a systolic and diastolic reading to see where it falls on the ACC/AHA blood pressure chart, with a plain-language explanation of what that category means.
Enter your values above to see your result and what it means.
Reading the blood pressure chart: systolic vs diastolic
Every reading has two numbers: systolic (the top number, pressure when your heart beats) and diastolic (the bottom number, pressure when your heart rests between beats). They are written as systolic over diastolic, for example 120/80, and measured in millimetres of mercury (mmHg). This calculator plots both numbers onto the standard category chart so you can see at a glance where a reading sits.
What is normal blood pressure?
Under the widely used ACC/AHA categories, a reading around 120/80 mmHg or below is generally described as normal, with higher bands labelled elevated and stages of hypertension. The category is decided by whichever number — top or bottom — falls into the higher band. Exact thresholds and how they apply to you can vary between guidelines and clinics, so compare this result with the values on your own report.
What is normal blood pressure by age?
Average blood pressure tends to drift upward with age as arteries stiffen, which is why "normal by age" is a common question. The standard category chart, however, uses the same thresholds for all adults rather than separate targets per decade. Older adults often see higher readings, but a higher number is not automatically "fine for your age" — context from a clinician matters.
What counts as high blood pressure (hypertension)?
High blood pressure means readings consistently above the normal band, grouped into elevated and hypertension stages on the chart. Because a single high reading can be caused by stress, caffeine, or a recent rush, categories are best judged from several measurements taken calmly over time. This tool interprets one reading at a time; it does not diagnose hypertension.
What is low blood pressure?
Low blood pressure (hypotension) is generally discussed when readings fall well below the normal range, sometimes around 90/60 mmHg or lower. It is usually only a concern when it comes with symptoms such as dizziness or fainting, and for some people a naturally low reading is simply their baseline. Use the category here as information and raise any persistent symptoms with a clinician.
How to get an accurate reading at home
Sit quietly for a few minutes with your back supported and feet flat, rest your arm at heart level, and avoid caffeine or exercise just before measuring. Take two or three readings a minute apart and note the pattern rather than relying on one number. Consistent technique makes the category this chart shows far more meaningful.
Frequently asked questions
Which number matters more, systolic or diastolic?
Both matter, and your category is set by whichever is higher. In adults over about 50, the systolic (top) number tends to be the stronger predictor of risk, but a raised diastolic on its own still places you in the corresponding category.
My reading was high once — do I have high blood pressure?
Not from one reading. Blood pressure varies a lot, and a single high value is often just that moment. Hypertension is diagnosed from an average of several readings on separate occasions, ideally including measurements taken at home or over 24 hours.
How should I measure my blood pressure at home?
Sit with your back supported and feet flat, rest for five minutes, keep the arm supported at heart height, and do not talk during the reading. Take two or three readings a minute apart and use the average. Avoid caffeine and exercise beforehand.
What is a hypertensive crisis?
A reading above 180 systolic and/or above 120 diastolic. First, recheck after a few minutes. If it stays that high and you have symptoms such as chest pain, breathlessness, vision change, or weakness, it is an emergency — call your local emergency number.