Health calculators

BP Calculator

Updated Sep 17, 2026 By Infinity Calculator
Rate Formulas Medical disclaimer
Enter your current blood pressure reading regardless of whether you are currently taking antihypertensive medication.
Your Reading
Whole number, 1–300 mmHg.
Whole number, 1–200 mmHg.
Whole number, 1–120 years.
Biological Sex
All results, the chart and the reference table convert to this unit.
Your classification

Stage 1 Hypertension (Mild)

Your reading: 145 / 92 mmHg
Pulse Pressure
53 mmHg
Normal range.
Mean Arterial Pressure (MAP)
109.7 mmHg
Elevated MAP — associated with increased cardiovascular workload.
Reading Summary
145 / 92
Systolic 145 mmHg over diastolic 92 mmHg.
Follow-Up & What This Means
Step-by-Step Solution
Your Values vs. Healthy Upper Limits
Blood Pressure Classification Reference
Category Systolic (mmHg) Diastolic (mmHg)

Introduction

This blood pressure calculator tells you what your reading means. Type in your top number (systolic) and bottom number (diastolic), plus your age and sex. It then names your category in plain words, anywhere from low blood pressure to hypertensive crisis.

You also get two extra numbers doctors use. Pulse pressure is the gap between your top and bottom numbers. Mean arterial pressure (MAP) is the average pressure in your arteries during one heartbeat. Both help show how hard your heart and blood vessels are working.

Enter your reading even if you take blood pressure medicine. You can work in mmHg or kPa, and switch units at any time. A chart compares your numbers to healthy limits, a table shows where you fall, and a step-by-step section shows the math.

This tool is for learning, not for diagnosis. Talk to your doctor about your results, and get help right away if you have chest pain, trouble breathing, vision changes, or a bad headache.

How to use our Blood Pressure Calculator

Enter your blood pressure reading, your age, and your sex. The calculator shows your blood pressure category, your pulse pressure, your mean arterial pressure (MAP), a follow-up tip, and a chart that compares your numbers to healthy limits.

Systolic Blood Pressure (top number): Type the top number from your reading. Pick mmHg or kPa in the box next to it. Use a whole number from 1 to 300 mmHg.

Diastolic Blood Pressure (bottom number): Type the bottom number from your reading. Pick mmHg or kPa. Use a whole number from 1 to 200 mmHg. This number must be lower than your top number.

Age (years): Type your age in whole years, from 1 to 120. Age helps explain results like isolated systolic hypertension and wide pulse pressure, which are more common in older adults.

Biological Sex: Choose Male or Female. This adds risk context to your result, since blood pressure patterns differ between men and women.

Show results in: Choose mmHg or kPa. Your results, the chart, and the reference table all switch to that unit.

Calculate: Click Calculate to see your blood pressure category and step-by-step math. Click Reset to clear your entries and start again.

What Is Blood Pressure?

Blood pressure is the force of blood pushing on the walls of your arteries as your heart pumps. It is written as two numbers, like 120/80 mmHg. High blood pressure (hypertension) often has no symptoms, so checking your numbers is the only way to know.

The Two Numbers

  • Systolic (top number): the pressure when your heart squeezes and pushes blood out.
  • Diastolic (bottom number): the pressure when your heart rests between beats.

Both numbers matter. If just one is high, your blood pressure is still counted as high.

Blood Pressure Categories

  • Low (hypotension): under 90/60 mmHg. Can cause dizziness or fainting.
  • Normal: about 90 to 120 over 60 to 80 mmHg.
  • Elevated: 121 to 129 systolic with diastolic under 80.
  • High normal: 130 to 139 over 80 to 89 mmHg.
  • Stage 1 high: 140 to 159 over 90 to 99 mmHg.
  • Stage 2 high: 160 to 179 over 100 to 119 mmHg.
  • Crisis: 180 or more, or 120 or more on the bottom. Get medical help right away.

Pulse Pressure and MAP

Pulse pressure is the top number minus the bottom number. A normal result is about 40 to 60 mmHg. A wide gap can mean stiff arteries, which is more common as people get older.

Mean arterial pressure (MAP) is the average pressure in your arteries over one heartbeat. It is found with this formula: MAP = diastolic + (pulse pressure ÷ 3). A normal MAP is about 70 to 100 mmHg. Doctors use MAP to see if blood is reaching your organs well.

Isolated Systolic Hypertension

This means the top number is 140 or higher while the bottom number stays under 90. It is common in adults over 60 because arteries get stiffer with age. It still raises heart and stroke risk and should be checked by a doctor.

How to Get an Accurate Reading

  • Rest quietly for 5 minutes first.
  • Sit with your back supported and feet flat on the floor.
  • Rest your arm on a table at heart level.
  • Skip coffee, smoking, and exercise for 30 minutes before.
  • Empty your bladder first and do not talk during the test.
  • Take two or three readings a minute apart and use the average.

Why It Matters

High blood pressure over time can damage your heart, brain, kidneys, and eyes. It raises the risk of heart attack, stroke, and kidney disease. The good news is that it can often be lowered by eating less salt, moving more, keeping a healthy weight, limiting alcohol, sleeping well, managing stress, and taking medicine if your doctor prescribes it.

Units: mmHg and kPa

Most countries measure blood pressure in millimetres of mercury (mmHg). Some use kilopascals (kPa). To change mmHg to kPa, divide by 7.5. For example, 120 mmHg is about 16 kPa.

This tool gives general health information only. It does not replace advice from a doctor. Always talk to a health professional about your own readings.

Formulas used

Pulse Pressure
PP = SBP - DBP
Mean Arterial Pressure
MAP = DBP + \frac{PP}{3} = DBP + \frac{SBP - DBP}{3}
Unit conversion: kPa to mmHg
P_{\text{mmHg}} = P_{\text{kPa}} \times 7.50062
Unit conversion: mmHg to kPa
P_{\text{kPa}} = \frac{P_{\text{mmHg}}}{7.50062}

Frequently asked questions

What is a normal blood pressure for my age?

For most adults, a healthy reading is under 120/80 mmHg. Doctors use the same goal for young and older adults, though many aim for under 130/80 mmHg in people over 65 who take medicine.

Children and teens have lower normal numbers that depend on age, height, and sex. A child's reading must be compared to growth charts, not adult limits.

Which number is more important, systolic or diastolic?

Both count, but they matter at different ages.

  • Under 50: a high diastolic (bottom) number is a strong warning sign.
  • Over 50: the systolic (top) number predicts heart attack and stroke risk better, because arteries stiffen with age.

If either number is high, your blood pressure is treated as high.

Why is my blood pressure higher in the morning?

Your body releases hormones like cortisol and adrenaline just before you wake up. They speed up your heart and tighten blood vessels, so blood pressure rises 10 to 20 mmHg in the early hours.

Blood pressure is usually lowest while you sleep and peaks in late morning. This is why doctors ask for both morning and evening readings.

Does coffee raise blood pressure?

Yes, but only for a short time. Caffeine can push systolic pressure up by about 5 to 10 mmHg for one to three hours.

Wait at least 30 minutes after coffee, tea, or energy drinks before you measure. Regular coffee drinkers often build some tolerance, so daily coffee has a smaller long-term effect.

What is white coat hypertension?

It means your blood pressure reads high at the clinic but is normal at home. Nerves about the visit cause the jump. It affects roughly 1 in 5 people who get a high clinic reading.

Home readings taken over 7 days, or a 24-hour monitor, help your doctor tell real hypertension from white coat readings.

Why is my blood pressure different in each arm?

A small gap is normal. A difference of up to 10 mmHg between arms happens in many healthy people.

A steady gap of 15 mmHg or more can point to narrowed arteries and should be checked. Once you know which arm reads higher, always use that arm for future checks.

How much does losing weight lower blood pressure?

About 1 mmHg for every kilogram (2.2 pounds) lost. Losing 10 kg can drop systolic pressure by roughly 5 to 10 mmHg.

Weight loss also helps blood pressure medicine work better and lowers your risk of diabetes.

How much does cutting salt lower blood pressure?

Dropping to under 1,500 mg of sodium a day can lower systolic pressure by about 5 to 6 mmHg. Even cutting 1,000 mg a day helps.

Most salt comes from packaged food, bread, sauces, and restaurant meals, not the salt shaker. Check labels for sodium.

Does exercise raise or lower blood pressure?

Both. During hard exercise, systolic pressure can climb to 160 to 200 mmHg, which is normal and short-lived.

Over weeks, regular activity lowers resting blood pressure by about 5 to 8 mmHg. Aim for 150 minutes of brisk walking or similar activity each week.

How often should I check my blood pressure at home?

If you are tracking high blood pressure, check twice a day for 7 days before a doctor visit: once in the morning before medicine and food, and once in the evening.

Take two readings a minute apart each time and record both. Ignore the first day's numbers, since they are often higher.

Are wrist blood pressure monitors as good as upper arm ones?

Upper arm cuffs are more reliable. Wrist arteries are narrower and closer to the skin, so readings shift if your wrist is not held at heart level.

If you use a wrist monitor, rest your arm on your chest at heart height. Also make sure any cuff fits your arm size, since a cuff that is too small can add 10 to 40 mmHg.

Can dehydration cause low blood pressure?

Yes. Less fluid in your body means less blood volume, so pressure falls. That can cause dizziness, weakness, and fainting when you stand up.

Drinking water often raises blood pressure within 15 to 30 minutes. Heavy sweating, vomiting, diarrhea, and some medicines can all trigger it.

Does high blood pressure cause headaches or nosebleeds?

Usually not. High blood pressure is called the silent killer because most people feel nothing for years, which is why regular checks matter.

Severe headaches, nosebleeds, chest pain, blurred vision, or trouble breathing with a reading of 180/120 mmHg or higher is an emergency. Get help right away.

How long does it take for lifestyle changes to lower blood pressure?

Eating less salt and following a diet rich in fruit, vegetables, and low-fat dairy can lower numbers in about 2 weeks.

Regular exercise shows results in 4 to 12 weeks. Keep the habits going, because blood pressure climbs back up if you stop.

Can I stop blood pressure medicine once my reading is normal?

No, not on your own. A normal reading usually means the medicine is working, not that the problem is gone. Stopping suddenly can send pressure back up fast.

Some people can lower their dose after big weight loss or diet changes, but only a doctor should make that call.

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