How to check blood pressure at home, and when to take the readings

Sit quietly for five minutes. Rest your bare upper arm on the table at the height of your heart, with the cuff snug just above the elbow. Do not talk. Take two readings one minute apart, in the morning and in the evening, at the same times every day, and write both down. The doctor wants the week’s average, not the best reading, so the routine matters more than any single number.

Which cuff

An automatic cuff for the upper arm that fits your arm. The American Heart Association recommends an automatic, cuff-style monitor for the upper arm, and says wrist and finger monitors are not recommended because they give less reliable readings.

Fit comes before brand. Measure around your upper arm and pick a monitor that comes with a cuff for that size; a cuff of the wrong size gives a wrong number. NICE NG136 puts the same rule on doctors’ own equipment: use an appropriate cuff size for the person’s arm.

Before you press start

For thirty minutes before the reading: no caffeine, no smoking, no exercise. Empty your bladder. Then sit for at least five minutes of quiet rest without talking or using the phone. All of that is the American Heart Association’s list for the half hour before a reading.

How to sit

Seated, quiet, with the arm outstretched and supported, is how NICE NG136 describes the position for a reading in the clinic or at home. The American Heart Association fills in the details: support the arm on a flat surface at heart level, put the middle of the cuff on the upper arm at heart level, and place the bottom edge of the cuff directly above the bend of the elbow, on bare skin. Remove the clothing over that arm first.

Which arm, and why the arms differ

Either arm. The American Heart Association says there is usually not a big difference between them. Pick one and keep using it, so the log compares like with like.

A difference does happen. NICE NG136 tells doctors to measure both arms when they consider a diagnosis, to repeat when the readings differ by more than 15 mmHg, and when the gap stays above 15 on the second measurement, to take every later reading on the arm with the higher number. If you notice such a gap at home, mention it at the appointment and use the higher arm from then on.

When to take the readings

Morning and evening, at the same times every day. NICE NG136 asks for readings twice daily, ideally in the morning and the evening, and the American Heart Association asks for the same time each day. Each time, take two readings one minute apart and write down both; the second one is not a correction of the first, it is half of the recording.

How many days

At least four days, ideally seven, says NICE NG136, and the readings from the first day are discarded before the rest are averaged. A full week gives 28 readings, of which 24 count. The average blood pressure calculator takes the list and gives back one average and its range; tick the first-day box and it drops the first two readings for you.

At home, ESC 2024 counts an average of 135/85 or higher as hypertension and a reading below 120/70 as non-elevated. Those are the lines the calculator uses.

What to do with a high reading

Sit for a minute and measure again. The American Heart Association says a single high reading is not an immediate cause for alarm, and that when readings are suddenly higher than 180/120, you wait at least one minute and test again; if they are still very high, you contact your doctor immediately. With chest pain, shortness of breath, back pain, numbness, weakness, a change in vision or difficulty speaking, that call is to emergency services. The blood pressure calculator shows the range for any one reading and repeats that conduct at the top of the range.

Everything below that line is a data point. Log it, keep the routine, and let the week decide.

Writing it down

Both readings, the time, the pulse, and a note when something was unusual. A page with those columns is enough for a week; the printable blood pressure log has them laid out with the measuring rules printed underneath. How to keep a blood pressure log explains how the doctor reads it.

BP Diary does the writing for you: it keeps each cuff reading with its time, adds the note, shows the average for the week, and prints the report. On a day without the cuff it can estimate a reading from your camera, calibrated against your cuff, so the week has no gaps; the cuff readings remain the ones the doctor relies on.