Blood Pressure Numbers Explained: What's Healthy at Every Age

Blood pressure is the force of blood pushing against the walls of your arteries. It's written as two numbers, such as 118/76 mm Hg (millimetres of mercury).

High blood pressure (hypertension) rarely causes symptoms, which is why it's often called a "silent" condition. Over time it strains the heart, blood vessels, kidneys and brain, raising the risk of heart attack, stroke and kidney disease.

What the two numbers mean

• Systolic (top number): the pressure in your arteries when your heart beats.
• Diastolic (bottom number): the pressure in your arteries when your heart rests between beats.

Both numbers matter. In adults over 50, a raised systolic number is especially linked with heart and stroke risk.

Blood pressure categories for adults

US guidelines from the American College of Cardiology and American Heart Association group readings like this:

• Normal: systolic under 120 and diastolic under 80
• Elevated: systolic 120–129 and diastolic under 80
• Stage 1 hypertension: systolic 130–139 or diastolic 80–89
• Stage 2 hypertension: systolic 140 or higher or diastolic 90 or higher
• Severe (hypertensive crisis): higher than 180 and/or higher than 120

Some other countries, including the UK and much of Europe, diagnose hypertension from 140/90 mm Hg. Your doctor will use the guideline followed where you live and look at your overall heart risk.

Is healthy blood pressure different by age?

Blood pressure tends to rise with age as arteries become stiffer, but that doesn't make high readings harmless. For most adults, the same categories apply whether you're 30 or 70.

Treatment targets can differ, though. In older adults, especially those who are frail or prone to dizziness and falls, doctors may set an individual target. Children and teens are assessed differently, using charts based on age, sex and height.

What counts as low blood pressure?

A reading below about 90/60 mm Hg is generally considered low (hypotension). Many healthy people naturally run low with no problems. It's worth seeing a doctor if low readings come with dizziness, fainting, blurred vision or confusion.

How to measure your blood pressure accurately at home

Home readings help you and your doctor see the real picture, since some people read higher in the clinic.

1. Avoid caffeine, exercise and smoking for 30 minutes beforehand.
2. Sit quietly for 5 minutes with your back supported and feet flat on the floor.
3. Rest your arm on a table at heart level and place the cuff on bare skin.
4. Take two readings, one minute apart, and write both down.
5. Measure at the same times each day, for example morning and evening.

How to lower high blood pressure

Lifestyle changes help everyone and may be enough on their own for elevated or stage 1 readings:

• Eat more vegetables, fruit, whole grains and low-fat dairy — the DASH eating pattern lowers blood pressure in studies.
• Cut back on salt. Most of it comes from packaged and restaurant food.
• Move regularly — aim for at least 150 minutes of moderate activity a week.
• Reach and keep a healthy weight. Even modest weight loss helps.
• Limit alcohol and stop smoking.

If your blood pressure stays high, your doctor may recommend medicine. Many effective, inexpensive options exist, and they work best alongside healthy habits.