What Is Blood Pressure?
Blood pressure is the force that blood exerts against the walls of your arteries as your heart pumps it around the body. It's one of the most commonly measured health indicators — and for good reason. Chronically elevated blood pressure (hypertension) is a leading risk factor for heart attack, stroke, and kidney disease, yet it often causes no symptoms at all.
Understanding what your reading means empowers you to take appropriate action — whether that's lifestyle adjustments, monitoring, or medical treatment.
Breaking Down the Numbers
A blood pressure reading is always expressed as two numbers, written as a fraction — for example, 120/80 mmHg.
Systolic Pressure (Top Number)
This measures the pressure in your arteries when your heart beats and pumps blood. It's the higher of the two values and represents the peak pressure in your circulatory system.
Diastolic Pressure (Bottom Number)
This measures the pressure in your arteries between heartbeats, when your heart is at rest and refilling. It represents the baseline pressure your blood vessels are under at all times.
Blood Pressure Categories
The following table summarises the standard blood pressure classifications used in clinical practice:
| Category | Systolic (mmHg) | Diastolic (mmHg) |
|---|---|---|
| Normal | Less than 120 | Less than 80 |
| Elevated | 120–129 | Less than 80 |
| Hypertension Stage 1 | 130–139 | 80–89 |
| Hypertension Stage 2 | 140 or higher | 90 or higher |
| Hypertensive Crisis | Higher than 180 | Higher than 120 |
| Low (Hypotension) | Less than 90 | Less than 60 |
Note: A single reading outside the normal range doesn't automatically mean you have hypertension. Your doctor will typically take multiple readings over time before making a diagnosis.
What Causes High Blood Pressure?
For most people, hypertension develops gradually over years with no single identifiable cause — this is called primary (essential) hypertension. Contributing factors include:
- Age (blood vessels naturally stiffen over time)
- Excess body weight
- High sodium intake
- Physical inactivity
- Chronic stress
- Tobacco use and heavy alcohol consumption
- Family history
Secondary hypertension is caused by an underlying condition such as kidney disease, thyroid disorders, or certain medications.
How to Get an Accurate Reading
Small mistakes in technique can significantly affect your result. For the most accurate home or clinic reading:
- Sit quietly for at least 5 minutes beforehand
- Avoid caffeine, exercise, and smoking for 30 minutes before measuring
- Sit with your back supported, feet flat on the floor, and arm at heart level
- Don't talk during the measurement
- Take two readings, one minute apart, and record both
When to See a Doctor
If your readings consistently fall in the Stage 1 or Stage 2 hypertension range, book an appointment with your doctor. A hypertensive crisis — readings above 180/120 — requires immediate medical attention, especially if accompanied by chest pain, shortness of breath, severe headache, or vision changes.
Regular monitoring is one of the simplest and most effective things you can do for long-term cardiovascular health.