What Do Blood Pressure Numbers Mean?
Blood pressure is written as two numbers — for example 120/80 mmHg:
- Systolic (top number): pressure in your arteries when your heart beats
- Diastolic (bottom number): pressure between beats when your heart rests
Both numbers matter. Either one being too high (hypertension) or too low (hypotension) can signal a health issue.
Blood Pressure Categories (Adults)
| Category | Systolic (mmHg) | Diastolic (mmHg) |
|---|---|---|
| Normal | Less than 120 | Less than 80 |
| Elevated | 120–129 | Less than 80 |
| High — Stage 1 | 130–139 | 80–89 |
| High — Stage 2 | 140 or higher | 90 or higher |
| Hypertensive Crisis | Higher than 180 | Higher than 120 |
| Low (Hypotension) | Less than 90 | Less than 60 |
Source: American Heart Association guidelines. mmHg = millimetres of mercury.
Normal Blood Pressure by Age
Blood pressure naturally rises with age as arteries stiffen. These are average healthy ranges:
| Age | Normal Systolic | Normal Diastolic |
|---|---|---|
| 18–29 years | 108–120 | 66–78 |
| 30–39 years | 111–122 | 68–80 |
| 40–49 years | 114–127 | 70–83 |
| 50–59 years | 116–131 | 71–84 |
| 60–69 years | 121–135 | 72–85 |
| 70+ years | 126–142 | 73–86 |
What High Blood Pressure Feels Like
Most people with high blood pressure have no symptoms at all — it is called the "silent killer" for this reason. Some people experience:
- Headaches (especially at the back of the head)
- Dizziness or lightheadedness
- Blurred or double vision
- Nosebleeds
- Shortness of breath
What Low Blood Pressure Means
Below 90/60 mmHg — Hypotension
Can cause dizziness, fainting, blurred vision and fatigue. Common causes include dehydration, heart problems, medications and prolonged bed rest.
Postural Hypotension
A drop in blood pressure when you stand up quickly, causing brief dizziness. Common in older adults and people on blood pressure medications.
Blood Pressure Tests Your Doctor Orders
| Test | What it checks |
|---|---|
| Blood pressure reading | Immediate systolic/diastolic measurement |
| 24-hour ambulatory BP monitoring | Average over a full day to rule out "white coat" hypertension |
| Urine test (ACR) | Checks for kidney damage from high blood pressure |
| eGFR / creatinine | Kidney function — hypertension can damage kidneys over time |
| Lipid profile | Cholesterol — often elevated alongside high blood pressure |
| Fasting blood glucose | Diabetes and hypertension frequently co-exist |
| ECG (electrocardiogram) | Checks for heart enlargement or rhythm problems |
How to Take an Accurate Reading
- Sit quietly for 5 minutes before measuring
- Sit with your back supported and feet flat on the floor
- Keep your arm at heart level, resting on a surface
- Avoid caffeine, exercise and smoking for 30 minutes before
- Take 2–3 readings, 1 minute apart, and record the average
- Measure at the same time each day for consistent tracking