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How to Interpret Blood Pressure Readings

There are many devices available for measuring your blood pressure. However, we will focus on how to use the automatic devices with sensors and digital displays. This is because these are readily available at your local pharmacy or medical supply store, and easy to use. These are good for measuring your blood pressure at home in a relaxed state. If done properly, this might give a more accurate measurement than when you are anxious, such as in your doctor's rooms. 


  • Firstly make sure your blood pressure monitor works properly. It should have working batteries and the arm cuff should fit well. The inflatable part of the cuff (bladder) should cover around 80% of your arm's circumference. 

  • It’s best to take your blood pressure sitting down with back support and legs uncrossed for at least 5 minutes before measuring.

  • Remove any barrier that might come between the cuff and your upper arm, so remove any long-sleeved clothing.

  • Sit back and relax - avoid talking or moving whilst carrying out the test. 

  • Extend one of your arms so it is at the level of your heart, place the cuff around it. Your arm should be supported in this position e.g. resting a table. 

  • Electronic blood pressure monitors require you to press a bottom to start measuring. The cuff will inflate and squeeze your arm tightly.

  • Once inflated, the cuff will stop then start deflating and a number will appear on the screen. A systolic (the larger number at the top) and a diastolic (the small number).

  • It is recommended you take 2 readings one minute apart to get an accurate reading.



Blood pressure is measured in millimeter of mercury (mmHg) and is given as 2 figures:

  • Systolic pressure – the pressure when your heart is contracted and pushes out blood

  • Diastolic pressure – the pressure when your heart relaxes and rested between beats

An example of a blood pressure reading is "120 over 80", or 120/80mmHg, it means you have a systolic pressure of 120mmHg and a diastolic pressure of 80mmHg.

As a general guide, high blood pressure is considered to be 140/90mmHg or higher (or an average of 135/85mmHg at home).

An “ideal” blood pressure is usually considered to be less than 120/80mmHg.

A blood pressure readings between 120/80mmHg and 140/90mmHg could mean you're at risk of developing high blood pressure if you do not take steps to keep your blood pressure under control.

These are generalized numbers that can change according to factors such as age, other existing conditions and every individual's normal blood pressure. Your doctor will be able to assess and develop a healthy blood pressure range for you.

It is important to constantly measure and keep a record of your blood pressure, so that when you see a medical professional, they can interpret your results accordingly. 


Written by Dr Ruusa Shivute | Health Window

Reference: Whelton PK, Carey RM, Aronow WS, et al. 2017 ACC/AHA/AAPA/ABC/ACPM/AGS/APhA/ASH/ASPC/NMA/PCNA Guideline for the Prevention, Detection, Evaluation, and Management of High Blood Pressure in Adults: A Report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines. Hypertension 2018; 71:e13.

April 14, 2021 |  Categories: Health WindowHigh Blood Pression / Hypertension

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