Two numbers, one slash between them, and most people have never had it properly explained. Here’s exactly what each figure in your reading represents.
Disclaimer: The information in this article is for general guidance only and does not constitute medical advice. Always consult a qualified healthcare professional about your own health and do not make changes to treatment or medication based solely on what you read here.
Key Takeaways
- A blood pressure reading always has two numbers: systolic and diastolic.
- Systolic is the top number, measured when your heart beats.
- Diastolic is the bottom number, measured when your heart rests between beats.
- Both numbers are written together in the format 120/80 mmHg.
- Neither number should be read in isolation.
Systolic and Diastolic Explained
Blood pressure numbers show how strongly blood is pushing against your artery walls. The top number is systolic pressure, measured when your heart beats, while the bottom number is diastolic pressure, measured between heartbeats. Here’s what each number in your reading actually stands for.
What Each Number Means
The systolic number, the one on top, measures the pressure in your arteries at the moment your heart contracts and pushes blood out. The diastolic number, the one on the bottom, measures the pressure in your arteries while your heart rests between beats. Together they’re written as systolic/diastolic mmHg, for example 118/76 mmHg.
Example Readings Explained
Here’s how that looks with a few real examples.
Putting It in Context
A reading of 110/70 mmHg sits comfortably within the normal range on both numbers. A reading of 138/88 mmHg falls into the elevated category. A reading of 150/95 mmHg would be classed as high stage 1 hypertension. Our [Blood Pressure Ranges and Readings] page breaks down every category these examples fall into.
This page is deliberately brief, it exists to answer one specific question clearly. For the fuller picture of what your numbers mean for your health, our [Blood Pressure Chart] page is the natural next stop.
Frequently Asked Questions
Here are quick answers to some common questions about blood pressure numbers.
What do the two blood pressure numbers mean?
The top number, systolic, measures pressure when your heart beats. The bottom number, diastolic, measures pressure when your heart rests between beats.
Which blood pressure number is more important?
Both matter, though systolic tends to get more clinical attention as it rises more predictably with age and carries more weight in long-term risk assessment.
What does 120 over 80 mean?
It means your systolic pressure is 120 mmHg and your diastolic pressure is 80 mmHg, which together sit right at the upper edge of the normal range.
Why is blood pressure always written as two numbers?
Because systolic and diastolic pressure reflect two different phases of your heartbeat, and both provide important, distinct information about your cardiovascular health.
