How to use this tool
- Sit quietly for five minutes, then take your reading with a validated upper-arm monitor.
- Type the systolic (top) and diastolic (bottom) numbers.
- Read your category. If the two numbers fall in different categories, the higher one applies.
Taking an accurate reading
Sit with your back supported and feet flat for five minutes before measuring. Rest your arm at heart level and use a cuff that fits your upper arm. Avoid caffeine, smoking and exercise for 30 minutes beforehand. Take two readings a minute apart and use the average. A single high reading doesn't mean you have hypertension; diagnosis needs repeated measurements.
US and UK thresholds differ
Since 2017 the American Heart Association and American College of Cardiology have defined hypertension from 130/80. The UK's NICE guideline uses 140/90 in the clinic, confirmed by home or ambulatory readings averaging 135/85 or more. Home readings run a little lower than clinic readings, partly because of "white coat" anxiety.
Pulse pressure and mean arterial pressure
Pulse pressure is systolic minus diastolic; a value persistently above about 60 mmHg in older adults can reflect stiff arteries. Mean arterial pressure (MAP), estimated as diastolic plus one third of the pulse pressure, is used in hospitals to judge blood flow to organs.
Frequently asked questions
What is a normal blood pressure?
Below 120/80 mmHg for adults.
Is 130/85 high blood pressure?
Under AHA categories it is stage 1 hypertension. Under UK NICE clinic thresholds it is below the diagnostic level. Repeat readings and discuss with a doctor.
When is blood pressure dangerously high?
Above 180/120, especially with symptoms such as chest pain or confusion. Seek urgent care.
What counts as low blood pressure?
Generally below 90/60, but it only needs attention if it causes symptoms.
Sources and references
- American Heart Association: Understanding blood pressure readings
- NICE guideline NG136: Hypertension in adults
- NHS: Low blood pressure (hypotension)