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How to Measure Blood Pressure at Home: A Step-by-Step Guide

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blood pressurehypertensionhome monitoringheart health

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High blood pressure usually causes no symptoms, so many people only find out at a check-up. If you measure blood pressure at home, you and your doctor get more information to work with, as long as you measure it correctly. The steps below follow guidance from Vietnam's Ministry of Health (Bộ Y tế), WHO, CDC and the NHS.

Why measure blood pressure at home?

According to the World Health Organization (WHO), most people with high blood pressure do not feel any symptoms, and the only way to know is to have it checked. WHO estimates that in 2024 about 1.4 billion adults aged 30 to 79 had hypertension, and about 44% of them did not know it. When it is not controlled, high blood pressure can damage the heart, the brain (stroke) and the kidneys.

MedlinePlus (U.S. National Library of Medicine) notes that home readings may be a better measure of your current blood pressure. Even so, WHO stresses that an assessment by a health professional is still important to judge your risk and any related conditions.

Choose the right monitor

  • Prefer an automatic monitor with an upper-arm cuff. The American Medical Association (AMA) recommends this type. A wrist monitor is a fallback only when an upper-arm cuff does not suit you. Finger devices are not recommended.
  • Choose a monitor validated for clinical accuracy (AMA). If you are not sure, ask your doctor or pharmacist.
  • Choose the right cuff size. Use a tape measure around the middle of your upper arm, in centimetres, and compare it with the size range printed on the cuff or the box (AMA). The Ministry of Health guideline says the inflatable bladder inside the cuff should be at least 80% of your arm's circumference in length and at least 40% in width.
  • Have the monitor checked regularly. The Ministry of Health notes that measuring devices should be calibrated periodically. MedlinePlus suggests bringing your monitor to appointments so your provider can check it.

Before you measure

  • Do not eat or drink anything for 30 minutes before (CDC).
  • Do not smoke, drink alcohol or coffee, or exercise just before. CDC says doing these within 30 minutes may raise your reading. The Ministry of Health advises avoiding coffee, tobacco and alcohol for 2 hours beforehand.
  • Empty your bladder (CDC).
  • Sit and rest for at least 5 minutes (CDC). The Ministry of Health advises 5 to 10 minutes of rest in a quiet room.
  • Wear a loose sleeve so the cuff can go directly on your skin.

Steps to measure blood pressure at home

  1. Sit properly. Use a chair with a back. Keep your back supported, both feet flat on the floor and your legs uncrossed (CDC).
  2. Support your arm at the right height. Rest your arm straight on a table, with the inside of the elbow level with your heart (Ministry of Health). Letting the arm hang down can raise the reading (CDC).
  3. Put the cuff on bare skin, not over clothing. It should be snug but not too tight (CDC). The lower edge of the cuff sits about 2 cm above the elbow crease (Ministry of Health).
  4. Stay still and do not talk while the monitor is measuring.
  5. Take at least two readings, 1 to 2 minutes apart (CDC, Ministry of Health). If the two readings differ by more than 10 mmHg, the Ministry of Health advises resting for more than 5 minutes and measuring a few more times.
  6. The first time, measure both arms. Use the arm with the higher reading from then on (Ministry of Health).
  7. Measure at the same time every day (CDC). The NHS describes taking readings in the morning and the evening for the number of days your doctor asks.
  8. Write down both numbers straight after each reading.

How to keep a blood pressure log

CDC recommends recording every reading in a log. The Ministry of Health says to write it as "systolic/diastolic", for example 126/82 mmHg, without rounding. A simple table is enough:

DateTime of dayReading 1Reading 2ArmNotes
Morning
Evening

Tips for a useful log:

  • Write down exactly what the monitor shows, including unusually high or low readings.
  • Note anything relevant: poor sleep, stress, headache, dizziness.
  • Bring the log and your monitor to every appointment.
  • The AMA recommends 7 days of home readings, but follow your doctor's advice on how many days.

What do home readings suggest?

Under the Ministry of Health's guideline on diagnosing and treating hypertension, the threshold for home self-measurement (several readings) is 135/85 mmHg or higher. That is lower than the 140/90 mmHg threshold for a reading taken correctly by a health worker. The NHS uses the same two levels.

Keep in mind:

  • One high reading is not enough to draw a conclusion. WHO says hypertension is diagnosed when readings are high on two different days.
  • Guidelines do not all use the same cut-offs. For example, CDC in the United States uses 130/80 mmHg. Let your doctor interpret your numbers.
  • If you are on treatment, ask your doctor before changing anything based on home readings.

When to contact your doctor soon

  • Your home readings are still high: MedlinePlus advises contacting your provider right away.
  • You often have headaches or blurred vision (NHS).
  • You have chest pain that comes and goes (NHS).
  • You have other symptoms you worry could be caused by high blood pressure (NHS).

When to call 115 straight away

WHO says very high blood pressure, usually 180/120 mmHg or higher, can cause severe headache, chest pain, dizziness, difficulty breathing, nausea, vomiting, blurred vision, confusion, nosebleeds or an abnormal heart rhythm.

Call 115 straight away, whatever the monitor shows, if you or someone with you has any of these signs:

  • Sudden pain or discomfort in the chest that does not go away (NHS).
  • Pain that spreads to the arm, neck, jaw, stomach or back (NHS).
  • Chest pain with sweating, feeling sick, light-headedness or shortness of breath (NHS).
  • Sudden numbness or weakness in the face, arm or leg, especially on one side of the body (CDC).
  • Sudden confusion, trouble speaking or difficulty understanding speech (CDC).
  • Sudden trouble seeing, trouble walking, dizziness or loss of balance (CDC).
  • Sudden severe headache with no known cause (CDC).

While you wait, note the time the symptoms started (CDC) and do not drive yourself to hospital (NHS).

Clinics can share this article with patients who need to monitor their blood pressure at home.

Sources

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