Blood pressure calculator that classifies your reading against AHA (American Heart Association) guidelines.
Four tabs: BP check (category + visual gauge), history and 7-day average (up to 10 readings), MAP (Mean Arterial Pressure), and a complete reference card.
Disclaimer: Not a substitute for medical diagnosis. Consult your doctor about blood pressure concerns.
Calculator information
📋 How to use this calculator
- Rest seated quietly for at least 5 minutes before measuring, empty your bladder, and avoid smoking or caffeine for 30 minutes beforehand.
- Sit with your back supported, feet flat on the floor (not crossed), and arm supported at heart level with the cuff on the upper arm (1-2 cm above the elbow).
- Take 2-3 measurements spaced 1-2 minutes apart, then enter the systolic (top) and diastolic (bottom) numbers in mmHg into the calculator.
- Click calculate to see the blood pressure category per AHA guidelines: normal (<120/80), elevated (120-129/<80), Stage 1 hypertension (130-139/80-89), Stage 2 (>=140/90), or crisis (>180/120).
- Use the MAP (Mean Arterial Pressure) tab to calculate average pressure: MAP = diastolic + (systolic - diastolic)/3.
- Tip: Log results in the history tab over 7 days (morning and evening) to see trends, rather than relying on a single measurement.
🧮 AHA Blood Pressure Categories and MAP
Normal: SBP <120 AND DBP <80 | Elevated: SBP 120-129 AND DBP <80 | Stage 1 Hypertension: SBP 130-139 OR DBP 80-89 | Stage 2 Hypertension: SBP >=140 OR DBP >=90 | Crisis: SBP >180 OR DBP >120 | MAP = DBP + (SBP - DBP)/3 | Pulse Pressure = SBP - DBP
- SBP = Systolic Blood Pressure (mmHg), pressure when the heart contracts
- DBP = Diastolic Blood Pressure (mmHg), pressure when the heart relaxes
- MAP = Mean Arterial Pressure (mmHg), average pressure during the cardiac cycle (normal 70-100)
- Pulse Pressure = difference between systolic and diastolic (normal 40-60 mmHg)
The 2017 ACC/AHA guideline lowered the hypertension threshold from 140/90 to 130/80. WHO still uses 140/90. Confirmed hypertension requires at least 2 separate measurements across 2 different visits.
💡 Worked example: Patient with a reading of 138/88 mmHg
Given:- Systolic pressure: 138 mmHg
- Diastolic pressure: 88 mmHg
- Age: 50 years
Steps:- Check category: SBP 138 falls in the 130-139 range AND DBP 88 in the 80-89 range
- AHA classification: Stage 1 Hypertension (requires lifestyle modification and possibly medication)
- Calculate MAP: 88 + (138 - 88)/3 = 88 + 50/3 = 88 + 16.67 = 104.67 mmHg
- MAP 104.67 is slightly above normal (70-100), indicating increased cardiac workload
- Pulse Pressure: 138 - 88 = 50 mmHg (still within the normal 40-60 range)
Result: Stage 1 Hypertension. MAP 104.67 mmHg (slightly elevated). Recommend consulting a physician, dietary modification (DASH diet), regular exercise, and reduced sodium intake.
❓ Frequently asked questions
What is the difference between systolic and diastolic blood pressure?
Systolic pressure (top number) is the pressure in the arteries when the heart contracts to pump blood, normally below 120 mmHg. Diastolic pressure (bottom number) is the pressure when the heart relaxes to refill, normally below 80 mmHg. Both numbers are important; systolic rises more noticeably in older adults due to arterial stiffening, while diastolic is more relevant in younger adults.
Which guideline should I follow, AHA 130/80 or WHO 140/90?
In the United States, the AHA/ACC 2017 guideline (130/80) is widely adopted by clinicians, and the CDC references it for population-level risk assessment. The WHO and European ESC still use 140/90. The stricter AHA threshold catches more at-risk patients earlier. Consult your physician because treatment decisions consider total cardiovascular risk factors, not just blood pressure numbers.
How do I measure blood pressure correctly at home?
Use a validated upper-arm digital monitor (not a wrist cuff), rest for 5 minutes before measuring, sit with your back supported and legs uncrossed, and keep your arm at heart level. Take 2-3 readings 1-2 minutes apart and average the 2nd and 3rd readings. Avoid talking, caffeine, or smoking for 30 minutes prior. Record morning and evening readings for 7 days before your doctor's appointment.
What are white coat hypertension and masked hypertension?
White coat hypertension is high blood pressure only at the clinic due to anxiety (around 15-30% of cases), while readings at home are normal. Masked hypertension is the opposite: normal at the clinic but elevated outside (10-15% of the population), which is risky because it often goes undetected. 24-hour Ambulatory Blood Pressure Monitoring (ABPM) or 7-day Home Blood Pressure Monitoring (HBPM) helps distinguish and diagnose both conditions.
How can I lower blood pressure without medication?
Proven lifestyle modifications: reduce sodium intake (target <2,300 mg/day, ideally <1,500 mg per AHA), follow the DASH diet (Dietary Approaches to Stop Hypertension) rich in fruits, vegetables, and low in saturated fat, do aerobic exercise 150 minutes/week, lose excess weight (each 1 kg lost reduces BP by about 1 mmHg), limit alcohol, quit smoking, manage stress through meditation or yoga, and get 7-9 hours of sleep. Combining these can lower BP by 5-10 mmHg.
📚 Sources & references
Last updated: May 11, 2026