Patient information from BMJ

Understanding your blood pressure reading

Last published:Apr 15, 2025

When your doctor tells you what your blood pressure is, they will give you two numbers. For example, your doctor may say that your blood pressure is '120 over 80'. This would be written as 120/80. 

• The first number is called the systolic pressure. It measures the highest level of pressure in your blood. This is when your heart beats to pump blood out around your body. 

• The second number is called the diastolic pressure. This is the lowest pressure in your blood vessels. It is measured when your heart relaxes between beats.

People usually find out they have high blood pressure (also called hypertension) after a routine blood pressure check. If you have a high reading, you’ll need to have your blood pressure measured again another time. This is because your blood pressure naturally goes up and down during the day. It can also go up if you are nervous. Repeating the test at another time or at home can confirm whether you have high blood pressure. You should also have your blood pressure measured in both arms. 

If these tests confirm that you have high blood pressure, your doctor will probably recommend changes to your lifestyle to help lower it. This could include changes to your diet, increasing exercise, and stopping smoking. Most people are also prescribed medicines to lower their blood pressure. There is more on this in our patient information called High blood pressure: what are the treatment options?

Here is a general guide as to what your doctor might recommend depending on how high your blood pressure is. However, treatment recommendations can vary from person to person. For example, if you have other health problems, such as kidney disease or diabetes, your doctor may want to start treatment earlier.

Blood pressure from 120 to 139 (systolic) or 85 to 89 (diastolic) 

This is sometimes called 'high-normal' blood pressure. It means you may have an increased chance of developing high blood pressure. Your doctor may give you advice on how to reduce your blood pressure by making some healthy changes to your lifestyle. For example, losing weight if you are overweight, and avoiding drinking too much alcohol.

Blood pressure from 140 to 159 (systolic) or 90 to 99 (diastolic)

This is sometimes called grade 1 hypertension. Your doctor will probably offer you drug treatment, as well as lifestyle advice. However, if you’re older (say, over age 80) your doctor may not recommend drug treatment unless your systolic pressure climbs to 150 or above. 

Blood pressure from 160 to 179 (systolic) or 100 to 109 (diastolic)

This is sometimes called grade 2 hypertension. Your doctor will probably offer you treatment with more than one drug, as well as lifestyle advice. 

Blood pressure at or above 180 (systolic) or 110 (diastolic)

This is called severe hypertension. It may also be called grade 3 hypertension, or hypertensive crisis. Your doctor will probably offer you treatment with more than one drug, as well as lifestyle advice. Occasionally people with severe hypertension will need emergency treatment in hospital.