Understanding your reading
Blood pressure has two numbers: systolic (pressure when your heart beats) over diastolic (pressure between beats), measured in mmHg. The categories below follow the American Heart Association classification for adults:
| Category | Systolic | Diastolic | |
|---|---|---|---|
| Normal | Below 120 | and | Below 80 |
| Elevated | 120–129 | and | Below 80 |
| High (Stage 1) | 130–139 | or | 80–89 |
| High (Stage 2) | 140 or higher | or | 90 or higher |
| Hypertensive crisis | Above 180 | and/or | Above 120 |
Note: under the 2017 ACC/AHA guideline used here, a reading of 120/80 already falls in Stage 1 because diastolic 80 crosses the threshold — older charts called this "normal", which surprises many people. Normal now requires below 120 and below 80.
One reading is a snapshot, not a diagnosis. Blood pressure moves with stress, caffeine, activity and time of day. Doctors diagnose hypertension from repeated readings on separate days — home measurements taken seated, rested, and at the same time each day are the most useful.
Protecting your heart: prevention that actually works
High blood pressure is the single biggest modifiable risk factor for heart attack and stroke — and it responds strongly to lifestyle:
- Eat DASH-style: vegetables, fruits, whole grains, dal and beans, low-fat dairy, nuts, and fish, while cutting salt to under about 5 g (1 tsp) per day.
- Potassium-rich foods — banana, coconut water, spinach, sweet potato, beans — help counter sodium's effect.
- Move daily: 150 minutes a week of brisk walking measurably lowers blood pressure; use our heart rate calculator to find your safe training zone.
- Watch weight, alcohol and smoking: each kilogram of excess weight lost lowers BP by roughly 1 mmHg; smoking and heavy alcohol both push it up. Check where you stand with the BMI calculator.
- Sleep and stress: chronic short sleep and unmanaged stress keep pressure elevated.
How to measure at home correctly
- Sit quietly for 5 minutes first, back supported, feet flat, arm at heart level.
- No caffeine, exercise or smoking for 30 minutes beforehand.
- Take two readings a minute apart and record both; morning and evening readings give the fullest picture.
Sources & references
- Whelton PK, et al. 2017 ACC/AHA Guideline for the Prevention, Detection, Evaluation, and Management of High Blood Pressure in Adults. Hypertension. 2018;71:e13–e115.
- Appel LJ, et al. A clinical trial of the effects of dietary patterns on blood pressure (DASH). N Engl J Med. 1997;336:1117–1124.
- World Health Organization. Guideline: Sodium intake for adults and children. 2012.