What do blood pressure readings mean?



A health check at the doctor invariably involves a blood pressure reading. Without taking these measurements, it's impossible to know whether your blood pressure is within the normal range or putting you at risk of cardiovascular disease (CVD).


And with cardiovascular diseases topping the list of health threats to men and women in the western world, more of us are starting to take an interest in monitoring our health.


Blood pressure is an important indicator of physical fitness. You may be familiar with the terms ‘high’ and ‘low’ blood pressure, but what does this really mean and what sort of readings should you be aiming for?


What is blood pressure?


Blood pressure is a measure of the force of blood being pumped by the heart against the arterial walls. This pressure takes into account both the strength of the heart muscle, the elasticity of the arterial walls and the volume and viscosity of the blood. Systolic blood pressure is the measure of blood flowing away from the heart and diastolic the measure of blood flowing back towards the heart.


Taking blood pressure readings


A typical blood pressure reading is done using the 'roll up your sleeve' type of monitor which involves wrapping a piece of material (cuff) around your upper arm. This is then inflated, either manually using a pump or automatically. The inflated cuff squeezes your arm to restrict the blood flow and stops once your pulse has been detected. It's not the most pleasant experience but it's a short-lived one and can it be life-saving.


Guide to blood pressure readings


Blood pressure readings are normally written showing the systolic reading over the diastolic reading in millimetres of mercury (mmHg). For example, 125 (systolic)/84 (diastolic), or 125mmHg/84mmHg. The ideal reading for a healthy adult’s blood pressure is less than 120/80, but anything between 120-129/80-84 is counted as normal.


High blood pressure is diagnosed when someone has a persistent reading higher than 140/90. This is called mild hypertension. Moderate hypertension is anything higher than 160/100, severe is greater than 180/110 and very severe is equal to or higher than 220/120.


Low blood pressure or hypotension is diagnosed with consistent readings of below 100/60 or the blood pressure is 25mmHg lower than it would normally be.


Remember that blood pressure readings can vary quite a bit throughout the day, so if your reading falls outside of the normal measurements, your doctor will probably take another reading soon after the first. They may ask you to come back at another time since diagnosis of high or low blood pressure is generally based on your average readings over a period of time.


Taking your blood pressure readings at home is often advised as this can help avoid 'white coat' syndrome – where blood pressure rises due to the 'fear or worry' of being at the doctors. Taking your blood pressure reading in the comfort of your home should produce a more accurate reading.


Some of the blood pressure monitors shown below are all Which? recommended Best Buys.


Omron M2 Basic Blood Pressure monitor: Which? best buy score 95%.

Very accurate, easy to use, large buttons, clear display. No date or time stamp, but it's easy enough to make a note of the readings.


Omron Wrist blood pressure monitor: Which? best buy score 91%.

Accurate, quick reading, light and comfortable.



Omron Evolve Automatic: Which? best buy score 93%.

Accurate and comfortable, with many extra features, including connection to a smart phone app. Can store readings for one user.


And finally the Boots Blood pressure monitor upper arm has a Which? score of 91%. It's accurate and easy to use but not as many features as some of the monitors shown above.