Blood Pressure Checker

About the Blood Pressure Checker

The blood pressure checker tells you what your reading means, which clinical category it falls into, and what action — if any — is recommended, based on the 2017 American Heart Association and American College of Cardiology guidelines that are now the standard reference across the US, UK, Australia, Canada, and New Zealand. Blood pressure is expressed as two numbers: systolic pressure (the higher number), which measures the force in your arteries when your heart beats and pumps blood; and diastolic pressure (the lower number), which measures the pressure between beats when your heart is resting and refilling. A reading of 120/80 mmHg is read as '120 over 80' and is the boundary between normal and elevated blood pressure under the current AHA/ACC classification. High blood pressure — hypertension — is one of the most significant modifiable risk factors for cardiovascular disease worldwide. It is often called the 'silent killer' because it typically produces no symptoms until serious damage has occurred to the heart, blood vessels, kidneys, or brain. Approximately one third of adults in the US, UK, Australia, and New Zealand have hypertension, and a substantial proportion are undiagnosed because they have never had their blood pressure checked or have had it checked infrequently. The 2017 reclassification by AHA/ACC lowered the Stage 1 hypertension threshold from 140/90 (the previous standard) to 130/80, creating a new 'elevated' category for readings of 120–129 systolic with diastolic below 80. This change was controversial but reflected strong evidence that cardiovascular risk begins increasing at blood pressures well below the old 140/90 threshold. Our calculator applies the current 2017 classification across six categories: Normal (below 120/80), Elevated (120–129 systolic, below 80 diastolic), Stage 1 Hypertension (130–139 systolic or 80–89 diastolic), Stage 2 Hypertension (140+ systolic or 90+ diastolic), Hypertensive Crisis (180+ systolic or 120+ diastolic), and Hypotension (below 90/60). The calculator also computes two clinically useful secondary measures. Mean Arterial Pressure (MAP) represents the average pressure in your arteries during a cardiac cycle and is calculated as diastolic + (systolic − diastolic) / 3. Normal MAP is 70–100 mmHg — values above 100 indicate significant cardiovascular stress, and values below 60 may indicate inadequate organ perfusion. Pulse Pressure (PP) is the difference between systolic and diastolic readings. Normal pulse pressure is 40–60 mmHg. A widened pulse pressure above 60 can indicate arterial stiffness, aortic regurgitation, or hyperthyroidism. A narrowed pulse pressure below 25 may indicate reduced cardiac output. Important measurement notes: a single reading is rarely sufficient for diagnosis. Blood pressure varies significantly throughout the day — it is typically lowest during deep sleep and highest in the morning. It rises with stress, caffeine, exercise, a full bladder, talking, and white-coat anxiety (the elevation that occurs in clinical settings due to nervousness). Most guidelines recommend confirming hypertension with multiple readings on different occasions, ideally including home monitoring. For an accurate reading: sit quietly for 5 minutes beforehand, use a properly sized cuff, position your arm at heart level, avoid caffeine and exercise in the 30 minutes prior, and do not talk during the measurement.

How It Works

Classification uses the 2017 AHA/ACC thresholds applied to the higher of systolic or diastolic classification. 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. Hypertensive Crisis: systolic > 180 OR diastolic > 120. Hypotension: systolic < 90 OR diastolic < 60. Mean Arterial Pressure (MAP) = Diastolic + (Systolic − Diastolic) / 3. Pulse Pressure = Systolic − Diastolic. Example: 135/88 mmHg. Systolic 135 = Stage 1 range. Diastolic 88 = Stage 1 range. Category = Stage 1 Hypertension. MAP = 88 + (135−88)/3 = 88 + 15.7 = 103.7 mmHg (slightly elevated). Pulse Pressure = 135 − 88 = 47 mmHg (normal range).

Tips & Best Practices

• ✓White coat hypertension — elevated readings in clinical settings due to anxiety — is very common. Home monitoring over several days gives a much more accurate picture of your true resting blood pressure than a single clinic reading.
• ✓The best time to measure blood pressure is in the morning before taking any medications and before coffee or exercise. Take two readings one minute apart and use the average. Repeat in the evening for a complete picture.
• ✓Sodium reduction is the single most evidence-supported lifestyle intervention for lowering blood pressure. Reducing daily sodium from 3,500mg (typical Australian/US intake) to below 2,000mg can lower systolic pressure by 5–10 mmHg — comparable to some medications.
• ✓The DASH diet (Dietary Approaches to Stop Hypertension) has strong clinical evidence for blood pressure reduction: rich in fruits, vegetables, whole grains, and low-fat dairy, while limiting red meat, added sugars, and sodium. In trials, DASH reduced systolic pressure by 8–14 mmHg.
• ✓Regular aerobic exercise of 150 minutes per week (30 minutes most days) reduces systolic blood pressure by an average of 5–8 mmHg in people with hypertension. Even a single 30-minute moderate walk produces a temporary reduction in blood pressure for several hours.
• ✓Hypertensive crisis (readings above 180/120) requires immediate medical attention if accompanied by any of: chest pain, shortness of breath, back pain, numbness or weakness, vision changes, or difficulty speaking. These may indicate a hypertensive emergency — stroke, aortic dissection, or acute heart failure.
• ✓Alcohol consumption raises blood pressure. More than two standard drinks per day is associated with significantly elevated blood pressure risk. Reducing from heavy to light drinking is estimated to lower systolic pressure by 3–4 mmHg.
• ✓Both arms may show different blood pressure readings — a difference of more than 10 mmHg between arms can indicate subclavian artery stenosis or other vascular issues and warrants medical investigation. Always use the same arm for monitoring consistency.

Who Uses This Calculator

Adults who have just measured their blood pressure at a pharmacy, doctor's office, or with a home monitor use the checker to understand what their reading means and whether they need to take action. People monitoring their blood pressure during a lifestyle change programme — reducing sodium, increasing exercise, losing weight — track their progress and understand when changes are moving them toward or away from the normal range. People with a family history of hypertension or cardiovascular disease use the checker to understand their reading in context of their personal risk profile. Pregnant women monitoring for pre-eclampsia — a dangerous rise in blood pressure during pregnancy — use the checker to understand when their readings warrant medical attention (140/90 or above during pregnancy requires immediate medical review). People who have been prescribed blood pressure medication track their response to treatment. Anyone who receives an unexpectedly high reading during a routine check-up uses the calculator to understand whether the reading warrants concern or is likely measurement error or white-coat effect.