Check your blood pressure reading against NHS guidelines and find out if it is normal, high, or low
This calculator is for informational purposes only and does not constitute medical advice. Always consult a qualified healthcare professional.
Blood pressure is one of the most important indicators of cardiovascular health. It measures the force of blood pushing against the walls of your arteries as your heart pumps it around your body. A blood pressure reading consists of two numbers: systolic pressure (the higher number, measured when your heart beats) and diastolic pressure (the lower number, measured between beats). Together, these numbers help determine whether your blood pressure falls within a healthy range. High blood pressure (hypertension) is a major risk factor for heart disease, stroke, kidney disease, and vascular dementia. It is often called the "silent killer" because it rarely causes noticeable symptoms until serious damage has occurred. According to the British Heart Foundation, around one in four adults in the UK has high blood pressure, and many are unaware of it. Regular monitoring is essential, and the NHS recommends that all adults over 40 have their blood pressure checked at least every five years. This calculator uses the standard NHS and British Heart Foundation (BHF) classification system to categorise your blood pressure reading. It provides immediate feedback on whether your reading is low, normal, elevated, or high, along with appropriate guidance on next steps.
To check your blood pressure reading: 1. Enter your systolic pressure (the top/higher number) in mmHg. This is the pressure in your arteries when your heart contracts and pushes blood out. A typical normal systolic reading is between 90 and 119 mmHg. 2. Enter your diastolic pressure (the bottom/lower number) in mmHg. This is the pressure in your arteries when your heart relaxes between beats. A typical normal diastolic reading is between 60 and 79 mmHg. 3. View your results. The calculator categorises your reading into one of six categories: Low, Normal, Pre-high (elevated), High (Stage 1), High (Stage 2), or Severe. It also provides a risk level and NHS guidance specific to your category. 4. Take action based on your reading. If your blood pressure is consistently elevated or high, book an appointment with your GP. A single high reading does not necessarily mean you have hypertension -- your GP will want to take multiple readings over time to confirm a diagnosis.
Blood pressure is categorised using established clinical thresholds from NHS and BHF guidelines. The classification uses both systolic and diastolic values, and the higher (worse) category of the two determines your overall classification: Low blood pressure: systolic below 90 OR diastolic below 60 mmHg. Low blood pressure (hypotension) is not usually a cause for concern unless it causes symptoms such as dizziness, fainting, or blurred vision. Normal blood pressure: systolic 90-119 AND diastolic 60-79 mmHg. This is the ideal range that indicates healthy cardiovascular function. Pre-high (elevated): systolic 120-139 OR diastolic 80-89 mmHg. Your blood pressure is higher than ideal but not yet classified as hypertension. Lifestyle changes can help prevent it from rising further. High -- Stage 1 (hypertension): systolic 140-159 OR diastolic 90-99 mmHg. This is the first stage of high blood pressure. Your GP may recommend lifestyle changes and possibly medication. High -- Stage 2 (hypertension): systolic 160-179 OR diastolic 100-109 mmHg. This is more significant hypertension that typically requires medication alongside lifestyle changes. Severe (hypertensive crisis): systolic 180 or above OR diastolic 110 or above. This requires urgent medical attention as it significantly increases the risk of stroke, heart attack, or organ damage.
Blood pressure naturally fluctuates throughout the day. It tends to be lower during sleep and rises upon waking. Various factors can temporarily raise your blood pressure, including stress, caffeine, exercise, smoking, and a full bladder. For the most accurate reading, sit quietly for five minutes before measuring, avoid caffeine and exercise for 30 minutes beforehand, and take readings at the same time each day. Home blood pressure monitors are widely available and recommended by the NHS for regular monitoring. When measuring at home, take two readings one minute apart and record both. If you are monitoring regularly, your GP will want to see an average of readings taken over several days. Reference: NHS Blood Pressure guidelines (nhs.uk/conditions/blood-pressure), British Heart Foundation Blood Pressure information (bhf.org.uk), NICE Hypertension guideline NG136.