Check Your Blood Pressure
Enter your systolic (top number) and diastolic (bottom number) blood pressure readings. Categories are based on American Heart Association guidelines.
Hypertensive Crisis -- Seek Immediate Medical Attention
A reading this high requires urgent medical care. If you are experiencing symptoms such as chest pain, shortness of breath, vision changes, or difficulty speaking, call emergency services immediately.
Guidance
Blood Pressure Categories Reference
The American Heart Association (AHA) defines five blood pressure categories for adults. The classification is based on the higher category between your systolic and diastolic readings.
| Category | Systolic (mmHg) | Diastolic (mmHg) | Action | |
|---|---|---|---|---|
| Normal | Less than 120 | and | Less than 80 | Maintain healthy lifestyle |
| Elevated | 120 -- 129 | and | Less than 80 | Adopt healthier habits |
| High BP Stage 1 | 130 -- 139 | or | 80 -- 89 | Lifestyle changes; talk to doctor about medication |
| High BP Stage 2 | 140 or higher | or | 90 or higher | Lifestyle changes plus medication likely needed |
| Hypertensive Crisis | Higher than 180 | and/or | Higher than 120 | Seek immediate medical attention |
Source: American Heart Association. When systolic and diastolic readings fall into different categories, the higher category applies.
Understanding Your Blood Pressure Reading
Blood pressure is measured in millimeters of mercury (mmHg) and written as two numbers separated by a slash. The first (top) number is systolic pressure -- the force against artery walls when your heart contracts. The second (bottom) number is diastolic pressure -- the pressure when your heart relaxes between beats.
Both numbers matter. A reading of 135/75, for example, would be classified as High Blood Pressure Stage 1 because the systolic value (135) falls in the 130--139 range, even though the diastolic value (75) is normal.
How to Get an Accurate Reading
Before measuring
- Avoid caffeine, exercise, and smoking for at least 30 minutes beforehand
- Empty your bladder
- Sit quietly for 5 minutes with your back supported and feet flat on the floor
- Rest your arm on a flat surface at heart level
During measurement
- Do not talk or move during the reading
- Place the cuff on bare skin, not over clothing
- Take 2--3 readings one minute apart and average the results
- Record the time, date, and both numbers for your doctor
When to measure
- Measure at the same time each day for consistency
- Morning readings (before medications) and evening readings are most useful
- Avoid measuring right after waking -- wait at least 30 minutes
- A single high reading does not necessarily mean you have high blood pressure
Factors That Affect Blood Pressure
Blood pressure is influenced by many factors, some controllable and others not:
| Modifiable Factors | Non-Modifiable Factors |
|---|---|
| Diet (sodium, potassium intake) | Age (risk increases with age) |
| Physical activity level | Family history and genetics |
| Body weight | Race and ethnicity |
| Alcohol consumption | Sex (males generally higher risk before 55) |
| Stress and sleep quality | Kidney structure and function |
| Smoking and tobacco use | -- |
Lifestyle Changes to Improve Blood Pressure
DASH Diet
The Dietary Approaches to Stop Hypertension (DASH) diet emphasizes fruits, vegetables, whole grains, lean proteins, and low-fat dairy while limiting saturated fat, sodium, and added sugars. Studies show it can lower systolic blood pressure by 8--14 mmHg.
Reduce Sodium Intake
Aim for no more than 2,300 mg of sodium per day (about 1 teaspoon of salt). Reducing to 1,500 mg may lower blood pressure further. Read nutrition labels, cook at home more often, and choose low-sodium alternatives.
Regular Physical Activity
Aim for at least 150 minutes of moderate-intensity aerobic exercise per week (such as brisk walking, swimming, or cycling). Regular exercise can lower systolic blood pressure by 5--8 mmHg.
Maintain a Healthy Weight
Losing even 5--10 pounds can reduce blood pressure. For each kilogram of weight lost, blood pressure may drop by about 1 mmHg.
Limit Alcohol and Quit Smoking
Moderate alcohol consumption (no more than 1 drink per day for women, 2 for men) and quitting smoking both contribute to lower blood pressure and reduced cardiovascular risk.
Frequently Asked Questions
What is blood pressure?
Blood pressure is the force of blood pushing against the walls of your arteries as your heart pumps. It is measured in millimeters of mercury (mmHg) and recorded as two numbers: systolic (pressure when the heart beats) over diastolic (pressure when the heart rests between beats). A reading of 120/80 mmHg is considered normal for most adults.
What do the two blood pressure numbers mean?
The top number (systolic) measures the pressure in your arteries when your heart contracts and pushes blood out. The bottom number (diastolic) measures the pressure when your heart relaxes and fills with blood between beats. Both numbers are important for assessing cardiovascular health.
What is a normal blood pressure reading?
According to the American Heart Association, normal blood pressure is a systolic reading below 120 mmHg AND a diastolic reading below 80 mmHg. If either number is higher, the reading falls into an elevated or high category.
When should I see a doctor about my blood pressure?
You should consult a healthcare provider if your blood pressure is consistently in the Elevated range (120--129 systolic) or higher. Stage 1 and Stage 2 readings may require medication in addition to lifestyle changes. If you ever record a reading above 180/120 (Hypertensive Crisis), seek immediate medical attention, especially if you have symptoms like chest pain, vision changes, or difficulty breathing.
Can blood pressure vary throughout the day?
Yes. Blood pressure naturally fluctuates throughout the day. It tends to be lowest during sleep, rises upon waking, and can spike temporarily due to stress, physical activity, caffeine, or posture. For the most accurate picture, measure at the same time each day under consistent conditions and track multiple readings over time.
How often should I check my blood pressure?
The AHA recommends adults with normal blood pressure check at least once a year during routine healthcare visits. If your blood pressure is elevated or you have been diagnosed with hypertension, your doctor may recommend checking daily or several times per week at home.
Is white coat hypertension real?
Yes. White coat hypertension refers to blood pressure that is elevated only in a clinical setting (like a doctor's office) but normal at home. This affects an estimated 15--30% of people diagnosed with high blood pressure. Home monitoring helps identify this pattern. Ambulatory blood pressure monitoring (a device worn for 24 hours) can also confirm the diagnosis.
Does this calculator store my data?
No. All calculations run entirely in your browser. No data is sent to any server, and nothing is stored.
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Privacy & Limitations
Privacy: This calculator runs entirely in your browser. No personal data -- including blood pressure readings or results -- is transmitted or stored anywhere.
Limitations: This tool classifies blood pressure based on American Heart Association guidelines for adults. It does not account for individual health conditions, medications, pregnancy, or pediatric ranges. Blood pressure categories may vary by medical organization and country. A single reading does not constitute a diagnosis. Always consult a qualified healthcare provider for medical advice.
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Blood Pressure Calculator FAQ
What is blood pressure?
Blood pressure is the force of blood pushing against the walls of your arteries as your heart pumps. It is measured in millimeters of mercury (mmHg) and recorded as two numbers: systolic (pressure when the heart beats) over diastolic (pressure when the heart rests between beats).
What do the two blood pressure numbers mean?
The top number (systolic) measures pressure in your arteries when your heart beats. The bottom number (diastolic) measures pressure in your arteries when your heart rests between beats. For example, a reading of 120/80 mmHg means 120 systolic and 80 diastolic.
What is a normal blood pressure reading?
According to the American Heart Association, normal blood pressure is a systolic reading below 120 mmHg AND a diastolic reading below 80 mmHg. This is written as less than 120/80 mmHg.
What are the blood pressure categories?
The AHA defines five categories: Normal (less than 120/80), Elevated (120-129 systolic and less than 80 diastolic), High Blood Pressure Stage 1 (130-139 systolic or 80-89 diastolic), High Blood Pressure Stage 2 (140+ systolic or 90+ diastolic), and Hypertensive Crisis (higher than 180 systolic and/or higher than 120 diastolic).
When should I see a doctor about my blood pressure?
You should consult a healthcare provider if your blood pressure is consistently elevated (120-129 systolic), in the high range (Stage 1 or Stage 2), or if you ever get a reading above 180/120 (Hypertensive Crisis), which requires immediate medical attention.
How often should I check my blood pressure?
The AHA recommends adults with normal blood pressure check at least once a year. If your blood pressure is elevated or high, your doctor may recommend more frequent monitoring, potentially daily home monitoring.
Can blood pressure vary throughout the day?
Yes. Blood pressure naturally fluctuates throughout the day. It is typically lowest during sleep and rises upon waking. Stress, physical activity, caffeine, and posture can all cause temporary changes. For the most accurate reading, measure at the same time each day while seated and relaxed.
Does this calculator store my data?
No. All calculations run entirely in your browser. No data is sent to any server, and nothing is stored.