What is blood pressure?
Blood pressure measures the force of blood against the walls of your arteries. It is expressed with two numbers: systolic (when the heart beats) and diastolic (when it rests). The calculator classifies your reading according to AHA guidelines and computes your mean arterial pressure.
A reading of 118/76 mmHg is classified as normal. At 135/85, the classification is hypertension stage 1 and it is worth consulting a doctor. Note: per the AHA, 120/80 is not normal — a diastolic of 80 already counts as stage 1.
AHA classification
| Category | Systolic | Diastolic | |---|---|---| | Normal | < 120 | < 80 | | Elevated | 120-129 | < 80 | | Hypertension Stage 1 | 130-139 | 80-89 | | Hypertension Stage 2 | ≥ 140 | ≥ 90 | | Hypertensive crisis | > 180 | > 120 |
Mean arterial pressure (MAP)
MAP = Diastolic + ⅓ × (Systolic − Diastolic)
A MAP between 70-100 mmHg is considered normal. It is a more accurate indicator of organ perfusion.
Step-by-step example
- Reading = 118/76 mmHg
- MAP = 76 + ⅓ × (118 − 76) = 76 + 14.0 = 90.0 mmHg (normal)
- AHA classification = Normal
Scenario table
| Systolic | Diastolic | Classification | MAP | |---|---|---|---| | 110 | 70 | Normal | 83.3 | | 125 | 78 | Elevated | 93.7 | | 135 | 85 | Stage 1 | 101.7 | | 145 | 95 | Stage 2 | 111.7 | | 185 | 125 | Crisis | 145.0 |
Hypertension is known as the "silent killer" because it usually shows no symptoms until it causes significant damage. Measuring your blood pressure regularly is key.
How to lower blood pressure naturally
- Reduce sodium: less than 2,300 mg/day (ideally 1,500 mg)
- Exercise: 150 minutes of moderate activity weekly
- Healthy weight: each kg lost can reduce ~1 mmHg
- Limit alcohol: maximum 1-2 drinks per day
- Manage stress: meditation, deep breathing
- DASH diet: rich in fruits, vegetables, and low in saturated fat
How to read the result
A single high reading is not a diagnosis: blood pressure varies with activity, stress, and time of day. If your reading falls in hypertension, measure several times on different days (always under the same conditions) before concluding. A hypertensive crisis (>180/>120) requires immediate medical attention.
This tool is educational and uses AHA guidelines as a reference; it does not replace a medical diagnosis. Classification may vary under other guidelines (ESC/ESH) and your clinical history.
Frequently asked questions
If normal, once a year is enough. If elevated or you have hypertension, your doctor may recommend weekly or daily measurements.
Yes. It is lower during sleep and rises on waking. Stress, exercise, caffeine, and food also affect it temporarily. Always measure under the same conditions.
If it exceeds 180/120 with symptoms (chest pain, shortness of breath), seek emergency care. Without symptoms, re-measure in a few minutes and consult your doctor.
It is the average pressure in the arteries during the cardiac cycle: MAP = diastolic + ⅓ × (systolic − diastolic). Between 70-100 mmHg is considered normal.
Related calculators
- Heart rate: pulse zones by age
- BMI: being overweight influences blood pressure
- Ideal weight: healthy weight range
- Daily calories (TDEE): activity and nutrition plan