What Do Your Blood Pressure Numbers Actually Mean?

Two numbers, two different things

A blood pressure reading of, say, 128/78 mmHg isn't one measurement, it's two. Each tells you something different about how hard your heart and arteries are working, and both matter.

Systolic (the top number) is the pressure in your arteries at the exact moment your heart contracts and pushes blood out. Diastolic (the bottom number) is the pressure that remains in between heartbeats, while your heart relaxes and refills.

Where do you sit?

| Category | Systolic (mmHg) | Diastolic (mmHg) | |----------|----------|-----------| | Normal | Below 120 | Below 80 | | Elevated | 120–129 | Below 80 | | High blood pressure (Stage 1) | 130–139 | 80–89 | | High blood pressure (Stage 2) | 140 or above | 90 or above |

A single reading rarely tells the full story. Blood pressure moves around throughout the day, and it can be pushed up temporarily by caffeine, stress, exercise, or simply the nervousness of being in a clinic ("white coat" effect) — which is exactly why one high number in a GP's office isn't, on its own, a diagnosis.

Why it's worth taking seriously

High blood pressure rarely causes symptoms, which is precisely what makes it dangerous — it does its damage quietly, over years, by straining the walls of your arteries. Left unchecked, it's a major contributor to heart attack, stroke, heart failure, kidney disease, and vascular dementia.

Getting a reliable answer

Because a single clinic reading can mislead in either direction, your doctor may suggest one of these to get a true picture:

• Ambulatory blood pressure monitoring — a cuff worn for 24 hours, taking readings automatically as you go about your normal day
• Home monitoring — using a validated home device over several days, ideally at the same times each day

Either approach gives a far more reliable average than a single number taken in a waiting room.

What actually moves the needle

Lifestyle first, for everyone:

• Cut back on salt — the Australian Heart Foundation recommends no more than about 5 grams of salt a day (roughly 2,000mg of sodium, or about one teaspoon), well below the average Australian intake
• Move regularly — aim for at least 150 minutes a week of moderate activity
• Watch your weight — even a modest, sustained loss can lower your readings meaningfully
• Keep alcohol within recommended limits
• Build meals around vegetables, fruit, and whole grains

Medication, when needed: if lifestyle changes alone aren't enough, or your numbers are significantly elevated, there are several well-established medication options. Which one suits you depends on your age, background, and any other health conditions you have.

The takeaway

Knowing your numbers, both of them, is the starting point. If you're consistently sitting above 130/80, it's worth a conversation with your doctor. High blood pressure is one of the most treatable risk factors in cardiology, and bringing it under control pays off for decades.