How to Check Blood Pressure at Home: Correct Method, Best Monitor and Target Readings

Measuring blood pressure at home gives a more reliable picture than occasional clinic readings, helps diagnose high blood pressure, shows whether treatment is working and can detect "white-coat" and "masked" hypertension. But a poor technique or an unreliable machine can give misleading numbers. These steps will help you get accurate readings.

Choosing a monitor

• Choose an automatic upper-arm monitor that has been clinically validated for accuracy. Look for validation by organisations such as the British and Irish Hypertension Society, the European Society of Hypertension, or the validateBP list from the American Medical Association.
• Make sure the cuff size fits your arm. A cuff that is too small gives falsely high readings. Measure your upper arm circumference; most adults need the standard size, but larger arms need a large cuff.
• Wrist and finger devices are less reliable and are not generally recommended unless you cannot use an arm cuff.
• Take your monitor to your doctor's clinic once to compare it with their readings.

Before you measure

• Avoid caffeine, smoking, alcohol and exercise for at least 30 minutes.
• Empty your bladder, as a full bladder can raise readings.
• Rest quietly for 5 minutes in a chair, without talking or looking at your phone.
• Sit with your back supported, feet flat on the floor and legs uncrossed.
• Rest your arm on a table so the cuff is at heart level.
• Remove tight sleeves, and place the cuff on the bare upper arm, with the tube running along the inside of the arm. Do not put it over clothes.

How to measure

1. Stay still and quiet, and do not talk during the reading.
2. Start the monitor and wait for the result.
3. Take two readings, one to two minutes apart, and note both.
4. Take the same arm each time, or use the arm with the higher reading if your doctor has found a difference.
5. Write down the date, time, both readings and your pulse. Many monitors store results, but a written or phone log is still useful.

When to measure

• For diagnosis or review: measure twice in the morning (before breakfast and medicines) and twice in the evening (before dinner), for 7 days. Discard the first day's readings and average the rest.
• For long-term monitoring: a few readings a week, or as your doctor advises.
• Take readings at the same times each day, so they can be compared.

What do the numbers mean?

Home readings tend to be slightly lower than clinic readings.

• Normal: below 130/80 mmHg
• High blood pressure (hypertension): an average of 135/85 or higher (about equal to 140/90 at the clinic)
• Very high: 180/120 or above, recheck after 5 minutes. If still very high, with chest pain, breathlessness, severe headache, vision changes or weakness, seek emergency help. Without symptoms, contact your doctor the same day.
• Low: below 90/60, especially with dizziness or fainting. See low blood pressure.

Use our blood pressure checker to see where your reading falls. A single high reading is not a diagnosis. The average over several days matters.

White-coat and masked hypertension

• White-coat hypertension: high in the clinic but normal at home. It may still raise long-term risk, so keep monitoring.
• Masked hypertension: normal in the clinic but high at home or during daily life. It is easy to miss without home monitoring and carries the same risk as sustained hypertension.

Common mistakes

• Measuring right after climbing stairs, drinking tea or smoking
• Talking or watching TV during the reading
• Cuff over clothing or too loose
• Back unsupported or legs crossed
• Arm hanging down rather than at heart level
• Measuring too often when anxious, which can raise readings
• Changing medicines because of one reading

Looking after your monitor

Replace batteries when low, keep the cuff clean and dry, and avoid folding the tube sharply. Have the machine checked against a clinic device every year or two.

What to do with the results

Bring your log, or the monitor, to your doctor appointments. Do not stop or change medicine because a single reading is low or high. Combine home monitoring with lifestyle changes. Read how to lower high blood pressure.

When to see a doctor

See a doctor if your average home blood pressure is 135/85 or higher, if readings are very different between visits, if you have symptoms such as persistent headache or dizziness, or if you are pregnant and have high readings, which need prompt assessment.

References

• European Society of Hypertension: practice guidelines for home blood pressure monitoring
• American Heart Association: how to measure blood pressure at home
• NICE guideline NG136: hypertension in adults
• British and Irish Hypertension Society: validated blood pressure monitors