Blood Pressure Calculator
Check your blood pressure category from your systolic and diastolic readings, using the 2025 American Heart Association guideline: normal, elevated or high.
🩺 Blood Pressure Check
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💡 How the Blood Pressure Calculator Works
Enter the two numbers from your blood pressure monitor and the calculator shows which category your reading falls into, using the categories in the 2025 American Heart Association (AHA) and American College of Cardiology (ACC) guideline. A reading of 120/80 mmHg is already stage 1 hypertension, because a diastolic of 80 meets the stage 1 threshold; normal is below 120/80.
What the two numbers mean
- Systolic (top number): the pressure in your arteries when your heart beats.
- Diastolic (bottom number): the pressure in your arteries when your heart rests between beats.
Both are measured in millimetres of mercury (mmHg) and written as systolic/diastolic, for example 118/76.
Blood pressure categories (AHA/ACC 2025)
| Category | Systolic (mmHg) | Diastolic (mmHg) | |
|---|---|---|---|
| Normal | Less than 120 | and | Less than 80 |
| Elevated | 120–129 | and | Less than 80 |
| Stage 1 hypertension | 130–139 | or | 80–89 |
| Stage 2 hypertension | 140 or higher | or | 90 or higher |
| Severe hypertension | Higher than 180 | and/or | Higher than 120 |
Example readings
| Reading | Category | Why |
|---|---|---|
| 118/76 | Normal | Both numbers in the normal range |
| 125/78 | Elevated | Systolic 120–129, diastolic under 80 |
| 128/84 | Stage 1 hypertension | Diastolic 80–89 moves it up to stage 1 |
| 136/72 | Stage 1 hypertension | Systolic 130–139 |
| 150/85 | Stage 2 hypertension | Systolic 140 or higher; the higher category applies |
| 132/92 | Stage 2 hypertension | Diastolic 90 or higher |
| 152/58 | Stage 2 hypertension | High systolic outweighs the low diastolic |
| 186/110 | Severe hypertension | Systolic higher than 180 |
| 88/58 | Low (hypotension) | Below 90/60 with no high number |
If your reading is higher than 180/120
The AHA advises waiting a minute and measuring again. If it is still this high and you have chest pain, shortness of breath, back pain, numbness, weakness, a change in vision or difficulty speaking, call emergency services: this may be a hypertensive emergency. Without any of these symptoms it is likely severe hypertension, and you should contact your doctor promptly.
Low blood pressure
The NHS describes low blood pressure as a reading below 90/60 mmHg. It often causes no problems, and many healthy people naturally run low. See a doctor if you keep getting symptoms such as dizziness, light-headedness, blurred vision or fainting, particularly when standing up. The calculator only reports low blood pressure when neither number is high, so a reading such as 152/58 is classed by its high systolic.
How to measure your blood pressure accurately
Based on CDC guidance:
- Don't eat or drink for 30 minutes beforehand, and empty your bladder.
- Sit in a chair with back support for at least 5 minutes before measuring, feet flat on the floor and legs uncrossed.
- Rest your arm on a table so the cuff is at chest height, with the cuff on bare skin of your upper arm and fitting snugly.
- Take at least two readings 1–2 minutes apart, at the same time each day.
- Use a validated upper-arm cuff. The 2025 guideline advises against relying on cuffless devices such as smartwatches for accurate readings.
One reading isn't a diagnosis
Blood pressure changes through the day with activity, stress, caffeine, pain and even talking. Doctors diagnose hypertension from an average of readings taken on separate occasions, often confirmed with home or 24-hour monitoring. Some people read high only in the clinic (white-coat hypertension), and others read normal in the clinic but high at home (masked hypertension). Keep a log of home readings to share with your doctor.
What the 2025 guideline recommends
- Treatment goal: below 130/80 mmHg for adults.
- Medication with lifestyle changes is recommended for adults whose average blood pressure is 140/90 or higher.
- At 130/80 to 139/89, medication depends on your health and risk: it is recommended for people with conditions such as cardiovascular disease, diabetes or chronic kidney disease, or a high estimated risk; otherwise, after 3–6 months of lifestyle changes if blood pressure stays at or above 130/80.
Only a doctor can decide whether you need treatment.
Lifestyle steps that lower blood pressure
The guideline recommends these for everyone with raised blood pressure:
- Keep a healthy weight; check yours with the BMI calculator.
- Follow a heart-healthy eating pattern such as DASH, with plenty of vegetables, fruit, whole grains and low-fat dairy.
- Reduce sodium (salt) and increase potassium from foods such as fruit, vegetables and beans.
- Be physically active; the heart rate zone calculator can help you pace moderate exercise.
- Reduce or avoid alcohol, and manage stress.
This calculator is for adults and is for information only. Children, teenagers and pregnant women use different thresholds. It does not diagnose any condition; discuss your readings with a doctor.
Sources
- American Heart Association: Understanding blood pressure readings
- American Heart Association: Top things to know, 2025 AHA/ACC high blood pressure guideline (Circulation and Hypertension, 14 August 2025)
- Centers for Disease Control and Prevention: Measuring your blood pressure
- NHS: Low blood pressure (hypotension)