How to Read a Blood Pressure Chart to Determine Your Risk of Hypertension

Medically reviewed by Carissa Stephens, RN, BSN, CCRN, CPN on March 20, 2017Written by Annette McDermott

What is blood pressure?

Blood pressure measures the extent of the force of blood on your blood vessel walls as your heart pumps. It’s measured in millimeters of mercury (mm Hg).

Systolic blood pressure is the top number in a reading. It measures the pressure on blood vessels as your heart squeezes blood out to your body. Diastolic blood pressure is the bottom number in a reading. It measures the pressure on blood vessels in between heart beats while your heart fills up with blood returning from your body.

It’s important to manage your blood pressure. Hypertension, or blood pressure that’s too high, can put you at risk for heart disease, kidney failure, and stroke. Blood pressure that’s too low, known as hypotension, can cause serious side effects, such as dizziness or fainting.

Know your blood pressure numbers

To manage your blood pressure, you need to know what blood pressure numbers are ideal and which are cause for concern. Following are the blood pressure ranges used to diagnose hypotension and hypertension in adults.

Systolic (top number)Diastolic (bottom number) Blood pressure category
90 or below60 or belowHypotension
91-12061- 80Normal
Between 120 and 139Between 80 and 89Prehypertension
Between 140 and 159Between 90 and 99Stage 1 hypertension
160 or higher100 or higherStage 2 hypertension
Higher than 180Higher than 110Hypertensive crisis

When looking at your numbers, only one of them needs to be too low or too high to put you in a hypertensive or hypotensive category. For example, if your blood pressure is 121/99, you’d be considered to have stage 1 hypertension.

Blood pressure levels for children

Blood pressure levels are different for children than they are for adults. Blood pressure targets for children are determined by several factors, such as:

  • age
  • gender
  • height

Talk to your child’s pediatrician if you’re concerned about their blood pressure. The pediatrician can walk you through the charts and help you understand your child’s blood pressure.

Learn more: How to understand blood pressure readings »

How to take a reading

There are a few ways to check your blood pressure. For example, your doctor can check your blood pressure in their office. Many pharmacies also offer free blood pressure monitoring stations. You can also check it at home using home blood pressure monitors. These are available for purchase from pharmacies and medical supply stores.

The American Heart Association recommends using an automatic home blood pressure monitor that measures blood pressure on your upper arm. Wrist or finger blood pressure monitors are also available, but they may not be as accurate.

When taking your blood pressure, make sure you:

  • sit still, with your back straight, feet supported, and legs uncrossed
  • keep your upper arm at heart level
  • make sure the middle of the cuff rests directly above the elbow
  • avoid exercise, caffeine, or smoking for 30 minutes prior

Learn more: Guide to checking blood pressure at home »

Treatment

Your reading may indicate a blood pressure problem even if only one number is high or low. No matter what category of blood pressure you have, it’s important to monitor it regularly. Check your numbers every day. Write the results in a blood pressure journal, and share them with your doctor. It’s a good idea to take your blood pressure more than once at one sitting, at least three minutes apart.

For high blood pressure

If you have a high systolic blood pressure, your doctor may watch it closely. This is because it’s a risk factor for heart disease.

Prehypertension is a condition that puts you at risk for hypertension. If you have it, your doctor may suggest lifestyle changes. Lifestyle changes such as eating a heart-healthy diet and exercising regularly may help bring your blood pressure numbers down. You may not need prescription drugs.

If you have stage one hypertension, your doctor may suggest lifestyle changes and medication. They may prescribe a drug such as a calcium channel blocker or beta-blocker.

Stage two hypertension may require treatment with lifestyle changes and a combination of medications.

Learn more: How to reduce your blood pressure »

For low blood pressure

Low blood pressure needs a different treatment approach. Your doctor may not treat it at all if you don’t have symptoms.

If your low blood pressure is caused by another health condition, such as a thyroid problem, dehydration, or diabetes, your doctor will likely treat that condition first.

If it’s unclear why your blood pressure is low, treatment options may include:

  • eating more salt
  • drinking more water
  • wearing compression stockings to help prevent blood from pooling in your legs
  • taking a corticosteroid such as fludrocortisone to help increase blood volume

Complications

Unmanaged high or low blood pressure may cause serious complications.

It’s hard to know when your blood pressure is high unless you’re monitoring it. High blood pressure doesn’t cause symptoms until you’re in hypertensive crisis. A hypertensive crisis requires emergency care. Left unmanaged, high blood pressure may cause:

On the other hand, low blood pressure may cause:

  • dizziness
  • fainting
  • injury from falls
  • heart damage
  • brain damage

Prevention

Lifestyle changes can help prevent high blood pressure. Try the following tips.

To lower blood pressure

  • Eat a heart-healthy diet that includes plenty of fruits and vegetables, whole grains, healthy fats, and low-fat protein.
  • Reduce your sodium consumption. The American Heart Association recommends keeping your sodium intake below 2400 mg with ideally no more than 1500 mg per day.
  • Watch your portions to help maintain a healthy weight.
  • Stop smoking.
  • Exercise regularly. If you aren’t currently active, start slowly and work your way up to 30 minutes of exercise most days.
  • Practice stress-relief techniques, such as mediation, yoga, and visualization. Chronic stress or very stressful events can send blood pressure soaring, so managing your stress may help manage your blood pressure.

Talk to your doctor

People with chronic, uncontrolled high blood pressure are more likely to develop a life-threatening condition. If you have low blood pressure, your outlook depends on its cause. If it’s caused by an untreated underlying condition, your symptoms may escalate.

You can reduce your risk of serious complications by managing your high or low blood pressure. This can involve lifestyle changes and medications, if prescribed. Talk to your doctor to find the best treatment for you.

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