Understanding your blood pressure reading
Blood pressure is measured in millimetres of mercury (mmHg) and is given as two figures:
Systolic pressure (Top Reading) – the pressure when your heart pushes blood out
Diastolic pressure (Bottom Reading) – the pressure when your heart rests between beats
For example, if your blood pressure is "140 over 90" or 140/90mmHg, it means you have a systolic pressure of 140mmHg and a diastolic pressure of 90mmHg.
As a general guide:
Normal blood pressure is considered to be between 90/60mmHg and 120/80mmHg
High blood pressure is considered to be 140/90mmHg or higher
Low blood pressure is considered to be 90/60mmHg or lower
A blood pressure reading between 120/80mmHg and 140/90mmHg could mean you're at risk of developing high blood pressure if you don't take steps to keep your blood pressure under control.