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Blood Pressure Calculator
Use this free blood pressure calculator to find what your reading means. Enter your systolic (top) and diastolic (bottom) numbers, and it sorts your reading into Normal, Elevated, Stage 1, Stage 2, or hypertensive crisis using the standard thresholds, with a gauge showing where you sit.
Enter the numbers exactly as your monitor shows them — systolic first, diastolic second, as in 120/80. One reading never diagnoses anything; the pattern over days and weeks is what matters.
Blood pressure gauge
Green is normal, amber is elevated or Stage 1, orange is Stage 2, and red is a crisis range. The needle moves with your systolic number.
How it works
Blood pressure is written as two numbers, like 120/80, and each one tells a different part of the story. The first number, systolic, is the pressure in your arteries when the heart beats and pushes blood out. The second, diastolic, is the pressure between beats, while the heart rests and refills. Both numbers matter, and your category is decided by whichever number falls in the higher range — so a reading of 135/85 is Stage 1 even though the diastolic number alone would sit in a lower band.
This blood pressure calculator sorts your reading into one of five categories used by the American Heart Association and the American College of Cardiology. The thresholds are the same ones doctors use in clinics, and they apply to adults. Children and teenagers use different charts based on age, sex, and height, so this calculator is for adults only.
Elevated: 120–129 and below 80
Stage 1 hypertension: 130–139 or 80–89
Stage 2 hypertension: 140 or higher, or 90 or higher
Hypertensive crisis: higher than 180 and/or higher than 120
Reading the table takes a little care. "Normal" means both numbers are in the normal range. "Elevated" means the top number has crept into the 120s while the bottom number is still under 80 — a warning sign, not yet high blood pressure. Stage 1 begins when the top number reaches 130 or the bottom number reaches 80. Stage 2 begins at 140 over 90. And a hypertensive crisis — higher than 180, or a bottom number higher than 120 — is a medical emergency, especially if it comes with chest pain, shortness of breath, back pain, numbness, vision changes, or trouble speaking.
A single reading never diagnoses high blood pressure. Pressure jumps around all day: it rises with exercise, stress, caffeine, and a full bladder, and it falls when you rest and sleep. Doctors diagnose hypertension from repeated readings over days or weeks, often with a home monitor or a 24-hour cuff. That is why the context of your reading matters — a number taken right after climbing stairs or drinking coffee can look alarming and mean very little, while the same number taken quietly at rest, morning and evening for a week, means a great deal.
To take a reading that means something, sit for five minutes first, feet flat on the floor, back supported, arm resting at heart level on a table. Use a cuff that fits — too small a cuff reads high — and put it on bare skin, not over a sleeve. Do not talk, cross your legs, or check your phone during the reading. Take two readings a minute apart and average them. Morning readings before food and medication, and evening readings before bed, give the most useful pattern, and writing them down — or using the notes field above — turns scattered numbers into a trend your doctor can actually use.
If your readings keep landing in Stage 1 or Stage 2, the usual first steps are the ones that help almost everyone: less salt, more movement, keeping weight steady, limiting alcohol, and not smoking. Many people bring Stage 1 readings down with those changes alone. But the decision about medication belongs to a doctor who can see your full history, your other risks, and your readings over time. This calculator sorts a number into a category; it does not diagnose you, and it cannot tell you whether you need treatment.
Worked example
Take a reading of 135 over 85, taken at rest while seated. Here is exactly what the calculator does.
Step 1 — Check the systolic number, 135. It falls in the 130–139 band, which is Stage 1 hypertension.
Step 2 — Check the diastolic number, 85. It falls in the 80–89 band, which is also Stage 1 hypertension.
Step 3 — Take the higher category. Both numbers point to Stage 1, so the reading is Stage 1 hypertension, and the gauge needle points into the amber Stage 1 zone.
Step 4 — Compare the neighbours. A reading of 118/76 would be Normal, because both numbers are below 120 and 80. A reading of 125/78 would be Elevated, because the top number is in the 120s while the bottom stays under 80. A reading of 145/92 would be Stage 2, and anything above 180/120 would be a hypertensive crisis needing urgent care. Enter 135 and 85 and the tool shows exactly Stage 1 hypertension with the gauge in the amber zone.
FAQ
What is a normal blood pressure reading?
A normal reading is below 120 over 80 — for example, 115/75. Readings in the 120s over a diastolic under 80 count as elevated, and 130/80 or above counts as high blood pressure. What matters most is the pattern of your readings over days and weeks, not any single number.
Why is my blood pressure higher at the doctor's office?
Many people read higher in a clinic than at home, a pattern called white coat effect. The unfamiliar setting, the rush to get there, and the nerves of the visit all raise pressure temporarily. Home readings taken quietly over a week are often lower and give a truer picture, which is why doctors ask patients to bring home logs.
Can one high reading mean I have hypertension?
No. A single high reading can come from exercise, stress, caffeine, pain, a full bladder, or a cuff that is too small. Hypertension is diagnosed from repeated readings over time, usually confirmed by a doctor with home monitoring or a 24-hour cuff. If one reading is very high, rest five minutes and take it again before drawing any conclusion.
What should I do if my reading is over 180/120?
If your reading is above 180/120 and you feel fine, rest for five minutes and take it again. If it is still that high, or if you have chest pain, shortness of breath, back pain, numbness or weakness, vision changes, or trouble speaking, seek urgent medical care right away. A hypertensive crisis is an emergency and should not wait for a routine appointment.
Does blood pressure change during the day?
Yes, quite a lot. It is usually lowest during sleep, rises in the morning, dips slightly in the afternoon, and varies with activity, meals, stress, and caffeine. That is why doctors compare readings taken at similar times of day and look at the average over a week, rather than reacting to one number.