Blood Pressure Chart & Reading Checker
Enter a reading and see which blood-pressure category it falls in, using the standard American Heart Association chart.
For information only — not a diagnosis. One reading is a snapshot; doctors look at the average of several, taken at rest. If you are worried about a reading, talk to a doctor.
What this calculates
A blood-pressure reading is two numbers. The top one, systolic, is the pressure in your arteries while your heart beats; the bottom one, diastolic, is the pressure while it rests between beats. Both are measured in millimetres of mercury (mmHg). The American Heart Association sorts adult readings into five bands — normal, elevated, high stage 1, high stage 2 and severe — and the important detail is that each number is judged on its own: whichever puts you in the higher band decides the category. A single reading moves with stress, caffeine, exercise and even talking during the measurement, so the category of one reading is a prompt to keep measuring, not a verdict.
Formula
Normal systolic < 120 and diastolic < 80 Elevated systolic 120–129 and diastolic < 80 Stage 1 systolic 130–139 or diastolic 80–89 Stage 2 systolic ≥ 140 or diastolic ≥ 90 Severe systolic > 180 or diastolic > 120 Pulse pressure = systolic − diastolic Mean arterial pressure = diastolic + pulse pressure ÷ 3
Example
A reading of 128/78 has a systolic number in the 120–129 band and a diastolic under 80, so it is Elevated. Change the bottom number to 82 and the reading becomes High — stage 1, even though the top number has not moved, because the diastolic number alone now reaches that band.
Frequently asked questions
What is a normal blood pressure?
For adults, below 120 systolic and below 80 diastolic — for example 115/75. Readings from 120 to 129 with a diastolic under 80 are called elevated; from 130/80 upwards the American Heart Association calls it high blood pressure.
Which number matters more, the top or the bottom?
Both count. The category is set by whichever number is in the higher band. In people over 50 the systolic number is usually the better guide to risk, but a high diastolic number on its own is still high blood pressure.
Why are my readings different every time?
Blood pressure changes minute to minute. Measure at the same times each day, seated and rested for five minutes, with your arm supported at heart level and without talking. Averages over a week or more say far more than any single reading.
When is a reading an emergency?
A reading above 180/120 should be re-checked after a few minutes' rest. If it stays that high, contact a doctor promptly. If it comes with chest pain, shortness of breath, back pain, numbness or weakness, a change in vision or difficulty speaking, call emergency services.
Does this calculator store my readings?
No. The calculation runs entirely in your browser and nothing you type is sent anywhere. To keep a history of readings privately, PressureKept stores them only on your own phone.