Blood Pressure Checker

Enter your systolic and diastolic readings to get your AHA blood pressure category, mean arterial pressure (MAP), pulse pressure, and colour-coded risk level.

A blood pressure checker interprets systolic and diastolic readings against the American Heart Association (AHA) and NICE (UK) classification thresholds, providing an immediate category, cardiovascular risk level, and action guidance. Blood pressure is expressed as systolic/diastolic mmHg — systolic is the pressure as the heart beats; diastolic is the pressure between beats. Both numbers matter independently. BMI Calculator and Daily Calories Calculator are companion tools for understanding weight and metabolic health in context.

This tool is designed for educational interpretation of readings taken with a validated home monitor or by a healthcare professional. A single reading is rarely diagnostic — blood pressure fluctuates throughout the day due to activity, stress, caffeine, posture, and white coat syndrome. The AHA recommends averaging two or more readings taken on separate occasions to classify blood pressure accurately.

Take your blood pressure reading with a validated arm-cuff monitor after 5 minutes of seated rest (do not take readings immediately after exercise, coffee, or stress).
Enter your systolic reading (the top, larger number) in the first field.
Enter your diastolic reading (the bottom, smaller number) in the second field.
Read the category, colour-coded by severity, and the accompanying guidance text.
Note your Mean Arterial Pressure (MAP) and Pulse Pressure — both are clinically useful supplementary metrics.

Blood pressure categories and formula explained

AHA / ACC 2017 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.

Mean Arterial Pressure (MAP) = (Systolic + 2 × Diastolic) ÷ 3. Normal MAP: 70–100 mmHg. A MAP below 60 mmHg indicates insufficient blood flow to vital organs. Pulse Pressure = Systolic − Diastolic. Normal: 40 mmHg. A wide pulse pressure (> 60 mmHg) may indicate arterial stiffness; a narrow pulse pressure (< 25 mmHg) may indicate reduced cardiac output.

Worked example: reading 128/82 → Elevated (systolic 120–129, diastolic < 80 fails because diastolic is 82, so this is Stage 1). MAP = (128 + 164) ÷ 3 = 97 mmHg (upper-normal). Pulse pressure = 46 mmHg (normal).

Understanding your blood pressure result

What your category means for cardiovascular risk

Normal (<120/<80): maintain through diet, exercise, and regular monitoring. Elevated (120–129/<80): lifestyle changes recommended; 50% likelihood of progressing to Stage 1 without intervention. Stage 1 (130–139/80–89): lifestyle changes mandatory; medication may be considered alongside cardiovascular risk factors. Stage 2 (≥140/≥90): medical consultation required, medication likely. Crisis (>180/>120): seek emergency medical care immediately — risk of stroke, heart attack, and organ damage is acute.

NICE UK guidelines classify hypertension at ≥140/90 in clinic readings and ≥135/85 on home/ambulatory monitoring, which is slightly different from AHA thresholds. This calculator uses AHA 2017 thresholds. Pair this tool with Protein Intake Calculator for a fuller picture of metabolic risk factors.

Health tips and best practices

Take readings at the same time each day — morning before medication and food, and evening before bed — for consistency.
Avoid caffeine, exercise, and smoking for 30 minutes before measuring.
Sit quietly for 5 minutes with feet flat on the floor and arm at heart height before taking a reading.
Reducing sodium intake to under 2,300mg/day (UK guideline: 6g salt) can lower systolic pressure by 5–7 mmHg.
30 minutes of moderate aerobic exercise 5 days per week is associated with a 4–9 mmHg systolic reduction.
The DASH diet has clinical evidence for reducing blood pressure by 8–14 mmHg systolic.

Hypertension affects approximately 1.28 billion adults globally (WHO, 2023) — roughly 1 in 3 adults.
In the UK, 1 in 4 adults has high blood pressure; only half are diagnosed.
Every 20 mmHg rise in systolic pressure doubles the risk of cardiovascular death (Lewington et al., Lancet).
Lowering systolic pressure by 10 mmHg reduces stroke risk by ~35% and coronary artery disease risk by ~25%.

Common mistakes to avoid

Using a wrist monitor instead of an arm-cuff monitor — wrist readings are less accurate for most people.
Taking a single reading after activity or stress and treating it as diagnostic.
Entering values reversed — systolic is always the higher number.
Ignoring isolated systolic hypertension (systolic ≥140, diastolic normal) — common in older adults and carries significant cardiovascular risk.

This calculator uses AHA/ACC 2017 blood pressure classification thresholds for educational purposes. It is not a medical device and cannot diagnose hypertension, hypotension, or any cardiovascular condition. Blood pressure classification requires multiple readings over time, assessed by a qualified healthcare professional in clinical context. A hypertensive crisis reading (>180/>120 mmHg) requires immediate emergency medical attention — do not use this tool as a substitute for calling emergency services. Always discuss blood pressure results and any treatment decisions with your GP or cardiologist.