Normal Blood Pressure Definition
Normal blood pressure is defined as less than 120 mm Hg systolic AND less than 80 mm Hg diastolic, based on the most recent ACC/AHA guidelines. 1
Current Blood Pressure Classification
The 2017 ACC/AHA guidelines provide the most recent authoritative classification system for blood pressure in adults:
- Normal BP: <120/<80 mm Hg 1
- Elevated BP: 120-129/<80 mm Hg 1
- Stage 1 Hypertension: 130-139/80-89 mm Hg 1
- Stage 2 Hypertension: ≥140/≥90 mm Hg 1
When systolic and diastolic pressures fall into different categories, always classify the patient according to the higher category. 1
Key Differences from Previous Guidelines
The 2017 ACC/AHA guidelines represent a significant shift from the older JNC 7 classification (2003), which defined normal BP as <120/<80 mm Hg but classified 120-139/80-89 mm Hg as "prehypertension" rather than distinguishing between "elevated" and "stage 1 hypertension." 1
The European guidelines (ESC/ESH) use different terminology but similar thresholds:
Clinical Significance of "Normal" Blood Pressure
Cardiovascular risk begins to increase continuously starting at 115/75 mm Hg, even within the "normal" range. 1 This means that while <120/<80 mm Hg is classified as normal, the relationship between BP and cardiovascular outcomes is a continuum without a clear threshold where risk suddenly begins. 1
For every 20 mm Hg increase in systolic BP or 10 mm Hg increase in diastolic BP above 115/75 mm Hg, there is a doubling of mortality from both ischemic heart disease and stroke. 1
Measurement Requirements
Blood pressure classification must be based on the average of ≥2 properly measured readings obtained on ≥2 separate occasions using validated equipment. 1 Single measurements should never be used to classify BP status. 1
Out-of-office BP measurements (home or ambulatory monitoring) should be used to confirm office readings and exclude white-coat hypertension. 1
Equivalent BP Values Across Settings:
- Office BP 120/80 mm Hg = Home BP 120/80 mm Hg = Daytime ambulatory 120/80 mm Hg 1
- Office BP 140/90 mm Hg = Home BP 135/85 mm Hg = Daytime ambulatory 135/85 mm Hg 1
Common Pitfalls to Avoid
Do not assume that BP in the 120-129/80-89 mm Hg range is "normal"—this is now classified as either "elevated" or "stage 1 hypertension" and carries increased cardiovascular risk. 1 Patients in this range have a 1.5-2.0 times higher risk of cardiovascular events compared to those with BP <120/80 mm Hg. 1
Do not use the term "prehypertension" when communicating with patients or in documentation—this terminology has been replaced by the more specific categories of "elevated BP" and "stage 1 hypertension." 1
Recognize that "normal" BP varies by measurement method—office readings tend to be higher than home or daytime ambulatory readings, so apply appropriate thresholds for each setting. 1