Blood pressure is one of the most commonly measured health values, yet many people leave the doctor’s office unsure what their reading actually means. Whether your GP mentioned a high reading, you are tracking it at home, or you simply want to understand the numbers better, this guide explains what blood pressure means, what is considered normal, and when it becomes a concern.
What Do the Two Blood Pressure Numbers Mean?
Blood pressure is expressed as two numbers, for example 120/80 mmHg. Each number represents a different phase of your heartbeat:
- Systolic pressure (the top number): The pressure in your arteries when your heart beats and pushes blood out
- Diastolic pressure (the bottom number): The pressure in your arteries when your heart rests between beats
Both numbers matter. High systolic pressure is the most common form of hypertension in adults over 50, while high diastolic pressure is more common in younger adults.
Blood Pressure Ranges: What Is Normal?
| Category | Systolic (mmHg) | Diastolic (mmHg) |
|---|---|---|
| Optimal | Less than 120 | Less than 80 |
| Normal | 120 to 129 | Less than 80 |
| High-Normal | 130 to 139 | 80 to 89 |
| Grade 1 Hypertension (mild) | 140 to 159 | 90 to 99 |
| Grade 2 Hypertension (moderate) | 160 to 179 | 100 to 109 |
| Grade 3 Hypertension (severe) | 180 or higher | 110 or higher |
| Low blood pressure (hypotension) | Less than 90 | Less than 60 |
These ranges are from the Heart Foundation of Australia and align with international guidelines. Your GP will interpret your reading in the context of your age, health history, and other risk factors.
What Is a Normal Blood Pressure by Age?
Blood pressure naturally tends to rise with age as arteries become stiffer. The following figures give a general guide, though individual variation is significant:
| Age Group | Typical Average (Men) | Typical Average (Women) |
|---|---|---|
| 18 to 29 | 119/70 | 110/68 |
| 30 to 39 | 122/73 | 116/71 |
| 40 to 49 | 127/77 | 122/74 |
| 50 to 59 | 133/80 | 130/78 |
| 60 to 69 | 136/81 | 135/79 |
| 70 and over | 140/82 | 139/80 |
Note: These are population averages for informational purposes. Your doctor will assess your individual reading based on your specific health context.
Factors That Can Cause a Temporarily High Reading
A single high blood pressure reading does not necessarily mean you have hypertension. Many factors temporarily elevate readings, including:
- White coat effect (anxiety in a medical setting can raise blood pressure by 10 to 20 mmHg)
- Caffeine within 30 minutes of measurement
- Exercise within 30 minutes of measurement
- Full bladder
- Cold temperature
- Talking during measurement
- Incorrect cuff size (too small gives artificially high readings)
This is why doctors typically take multiple readings on separate occasions before diagnosing hypertension.
How to Take an Accurate Home Blood Pressure Reading
Home monitoring is increasingly recommended by GPs for diagnosing and managing blood pressure. To get an accurate reading:
- Sit quietly for at least 5 minutes before measuring
- Place your arm at heart height on a flat surface
- Use the correct cuff size for your arm circumference
- Do not talk, cross your legs, or hold your breath during the measurement
- Take two readings, one minute apart, and record the average
- Measure at the same time each day (morning before medications and evening are recommended)
- Avoid caffeine, exercise, and smoking for 30 minutes beforehand
Why Does High Blood Pressure Matter?
Hypertension is sometimes called a “silent condition” because most people have no symptoms. Left untreated, sustained high blood pressure significantly increases the risk of heart attack, stroke, kidney disease, and damage to the eyes and blood vessels.
Reassuringly, blood pressure is highly manageable with lifestyle changes and, where necessary, medication. Even a modest reduction in systolic pressure (around 10 mmHg) meaningfully reduces cardiovascular risk.
Understanding Your Blood Pressure Results with NORMA
NORMA can help you make sense of blood pressure readings in the context of your health history. If your GP has mentioned elevated blood pressure and you want to understand what it means, what the next steps typically are, and what questions to bring to your next appointment, NORMA can walk you through that.
NORMA does not replace your doctor. It helps you go into every appointment better informed and more confident in the conversation you need to have.
Frequently Asked Questions
What is considered dangerously high blood pressure?
A reading of 180/120 mmHg or higher is a hypertensive crisis and requires immediate medical attention, particularly if accompanied by symptoms such as severe headache, chest pain, shortness of breath, or visual changes. Seek emergency care immediately.
What is considered low blood pressure?
A reading below 90/60 mmHg is generally considered low. Low blood pressure is only a problem if it causes symptoms such as dizziness, fainting, blurred vision, or fatigue. Many fit, healthy people have naturally low blood pressure with no symptoms at all.
Should I take blood pressure medication if I have high readings at home?
This is a decision for your GP based on your individual results, risk profile, and whether lifestyle changes have been trialled first. Bring your home monitoring log to your appointment so your doctor has a full picture of your readings over time.