What Is a Normal Blood Pressure? Understanding Your Numbers

A blood pressure below 120/80 mmHg is generally considered an optimal or healthy reading. Understanding your numbers also means knowing how hypertension is diagnosed and what target is right for you.

Australia · 27 October 2026 · 6 min read

For most adults, a blood pressure below 120 mmHg systolic and 80 mmHg diastolic is generally considered an optimal or healthy reading. But a reading above this range does not automatically mean you have hypertension. The local guidance discussed below generally uses repeated clinic readings of 140 mmHg systolic or higher, or 90 mmHg diastolic or higher, to diagnose hypertension. A single reading should not be interpreted in isolation: your pattern over time, measurement technique, medical history and overall cardiovascular risk all matter.

In Australia, the Heart Foundation advises that your ideal blood pressure depends on your medical history. Your GP can help interpret your readings and decide whether home or 24-hour monitoring would be useful.

What do the two blood pressure numbers mean?

Blood pressure is written as two numbers measured in millimeters of mercury (mmHg), for example, 120/80 mmHg.

• Systolic (Top Number): Measures the pressure in your blood vessels when your heart contracts and pumps blood out.

• Diastolic (Bottom Number): Measures the pressure in your blood vessels when your heart rests between beats.

Both numbers matter when assessing cardiovascular health. If your systolic and diastolic readings fall into different categories, the higher category is generally used when interpreting the result.

What blood pressure is considered normal?

According to the Australian Heart Foundation’s hypertension guideline, a reading below 120 mmHg systolic and 80 mmHg diastolic is optimal. Some readings above this level are still classified as normal or high-normal rather than hypertension. Your clinician can explain how the category relates to your own cardiovascular health.

Readings below 90/60 mmHg are commonly described as low blood pressure. They do not always cause problems, but recurring dizziness, fainting or weakness should be discussed with a healthcare professional.

The table below describes clinic readings in adults. If the two numbers fall into different categories, use the higher category. These categories are not individual treatment targets, and diagnosis requires clinical assessment.

What is considered high blood pressure?

The Heart Foundation guideline uses clinic systolic pressure of 140 mmHg or higher and/or diastolic pressure of 90 mmHg or higher when assessing hypertension. Your GP may use repeated measurements, home readings or ambulatory monitoring to confirm the pattern and assess your overall cardiovascular risk.

A category describes the reading, not your treatment plan. Whether you need lifestyle changes, medication or further tests depends on repeated measurements, your overall cardiovascular risk and your clinician's assessment.

A very high reading needs prompt medical advice. Seek emergency medical care if you have symptoms such as chest pain, severe breathlessness, sudden weakness, difficulty speaking or sudden vision changes. Do not wait for another reading if you have emergency symptoms.

What if the top and bottom numbers fall into different categories?

When your systolic and diastolic numbers fall into different categories, clinical guidelines evaluate your overall category based on whichever number is higher.

For example:

• 118/84 mmHg: The diastolic reading puts this in the normal clinic category, rather than the optimal category.

• 142/78 mmHg: The systolic reading is in grade 1 hypertension range, despite the lower diastolic reading. A clinician would assess repeated readings before confirming a diagnosis.

Does normal blood pressure change with age?

Blood pressure often rises with age, but a higher reading should not simply be dismissed as normal ageing. The clinic categories above are a starting point for understanding adult readings, not a personal treatment target.

The target your clinician recommends may depend on your age, frailty, symptoms, medical history and how well you tolerate treatment. Track your readings and discuss the pattern with your primary-care clinician.

Why can blood pressure readings be different each time?

Blood pressure is dynamic and fluctuates constantly throughout the day in response to physical activity, stress, caffeine intake, smoking, and even posture or bladder fullness.

Because temporary spikes are common, a single higher reading does not necessarily show a lasting change. The Heart Foundation recommends a validated monitor, five minutes of quiet sitting, a supported back and arm, and both feet flat on the floor. Take two readings one minute apart and record them to discuss with your GP.

Home averages are interpreted differently from clinic readings. In the guidance cited here, a home average of 135 mmHg systolic or higher and/or 85 mmHg diastolic or higher is used when assessing hypertension. Ask your clinician which measurements and targets apply to you.

Separately, the US 2025 AHA/ACC guideline advises against relying on cuffless devices, including smartwatches, for accurate blood pressure measurement until they demonstrate greater precision and reliability.

If you've been taking readings over time alongside your health screening reports, you can add them to your health locker in the Genie app with wearable data such as activity, sleep and resting heart rate. With Ask Genie, you can explore how your readings sit within your broader health picture and what patterns may be worth discussing with your healthcare professional.

Note: This content is for general informational purposes only and is not medical advice, diagnosis or treatment. It does not replace consultation with a qualified healthcare professional. If you have concerns about your heart health, please consult a qualified physician.

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