Blood Pressure Category Calculator
Classify your blood pressure reading into Normal, Elevated, Stage 1, or Stage 2 Hypertension using AHA guidelines. Use it after taking a reading at home or at the doctor's office.
About this calculator
Blood pressure is recorded as two numbers: systolic (the pressure when your heart beats) over diastolic (the pressure between beats), both in mmHg. The American Heart Association defines four categories based on these values. Normal: systolic < 120 AND diastolic < 80. Elevated: systolic 120–129 AND diastolic < 80. Stage 1 Hypertension: systolic 130–139 OR diastolic 80–89. Stage 2 Hypertension: systolic ≥ 140 OR diastolic ≥ 90. The logic follows: if systolic ≥ 140 OR diastolic ≥ 90 → Stage 2 Hypertension; else if systolic ≥ 130 OR diastolic ≥ 80 → Stage 1 Hypertension; else if systolic < 120 AND diastolic < 80 → Normal; otherwise → Elevated. A single elevated reading is not a diagnosis — consistent readings over time are clinically meaningful.
How to use
Suppose your blood pressure reading is 135/85 mmHg, meaning systolic = 135 and diastolic = 85. Step 1: Check Stage 2 threshold — is 135 ≥ 140 or 85 ≥ 90? No. Step 2: Check Stage 1 threshold — is 135 ≥ 130 or 85 ≥ 80? Yes (both conditions are true). Result: Stage 1 Hypertension. This means your doctor may recommend lifestyle changes such as reducing sodium intake, increasing physical activity, and monitoring your blood pressure regularly before considering medication.
Frequently asked questions
What is the difference between Stage 1 and Stage 2 Hypertension?
Stage 1 Hypertension is defined as a systolic reading of 130–139 mmHg or a diastolic reading of 80–89 mmHg. Stage 2 Hypertension is more severe, with systolic at or above 140 mmHg or diastolic at or above 90 mmHg. Stage 1 is typically managed with lifestyle changes first, while Stage 2 often requires medication in addition to lifestyle modifications. Both stages increase the risk of heart disease, stroke, and kidney damage if left untreated.
How do I know if my blood pressure reading is normal?
A normal blood pressure reading is defined as a systolic pressure below 120 mmHg AND a diastolic pressure below 80 mmHg. If your systolic is between 120 and 129 while your diastolic remains below 80, your reading is classified as Elevated — a warning sign that hypertension may develop. Consistent normal readings indicate a healthy cardiovascular baseline, but you should still measure regularly since blood pressure can change with age, diet, and stress levels.
Why does only one number need to be high to trigger a hypertension category?
Blood pressure categories use an OR condition for hypertension thresholds because either the heart working too hard during a beat (high systolic) or insufficient relaxation between beats (high diastolic) independently stresses the cardiovascular system. Either condition alone is enough to damage arteries and organs over time. This is why a reading of 125/92 would still be classified as Stage 2 Hypertension despite the systolic being in a normal range — the diastolic value alone crosses the threshold.