Normal Blood Pressure Definition
Normal blood pressure is defined as systolic BP <120 mm Hg AND diastolic BP <80 mm Hg in adults, measured properly in the office setting. 1
Current Classification Standards
The most recent ACC/AHA guidelines (2017) establish a clear four-tier classification system that differs from older European standards 1:
ACC/AHA Classification (2017):
- 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
ESC/ESH Classification (2018):
- Optimal BP: <120/<80 mm Hg 1
- Normal BP: 120-129/80-84 mm Hg 1
- High Normal BP: 130-139/85-89 mm Hg 1
- Grade 1 Hypertension: 140-159/90-99 mm Hg 1
Key Measurement Requirements
For accurate classification, blood pressure must be measured correctly 1:
- Average of ≥2 readings obtained on ≥2 separate occasions 1
- Patient seated and relaxed 2
- Properly calibrated, validated equipment 1
- Appropriate cuff size (bladder width 40% of mid-arm circumference) 2
When systolic and diastolic values fall into different categories, always classify the patient according to the higher category 1, 2
Out-of-Office Blood Pressure Equivalents
Office measurements may not reflect true blood pressure status, so corresponding home and ambulatory values are critical 1:
Normal BP Equivalents:
- Office: 120/80 mm Hg
- Home: 120/80 mm Hg
- Daytime ambulatory: 120/80 mm Hg
- Nighttime ambulatory: 100/65 mm Hg
- 24-hour ambulatory: 115/75 mm Hg 1
Clinical Significance of Normal BP
Cardiovascular risk begins to increase continuously above 115/75 mm Hg 1, making truly normal blood pressure (<120/<80 mm Hg) the optimal target for long-term health 1.
Only approximately 20% of middle-aged Americans maintain optimal blood pressure levels 3. Among US adults, the prevalence of normal BP decreases dramatically with age: 57.8% in those 18-44 years, 25.3% in those 45-64 years, 11.2% in those 65-74 years, and only 5.0% in those ≥75 years 4.
Adults with normal BP versus elevated BP/hypertension demonstrate:
- Lower rates of diabetes, albuminuria, atherosclerotic cardiovascular disease, and heart failure 4
- Association with healthy lifestyle factors including physical activity ≥150 minutes/week, normal weight or overweight (versus obesity), and moderate or no alcohol consumption 4
Common Pitfalls to Avoid
White coat hypertension affects 15-20% of people with apparent stage 1 hypertension 1. Confirm office hypertension with out-of-office measurements (home BP monitoring or ambulatory BP monitoring) before establishing a diagnosis 1.
Do not diagnose hypertension based on a single visit 1. Multiple readings over time are essential, as blood pressure variability is the rule rather than the exception 1.
In adolescents ≥13 years, use the same adult thresholds (<120/<80 mm Hg for normal BP), but require elevated readings on three separate occasions before establishing a hypertension diagnosis 2.