Blood pressure

How to measure blood pressure at home

September 20267 min read

Has your doctor asked you to measure your blood pressure at home for a few days? Here is the method described by the European guidelines (ESH) and the American Heart Association: which monitor to use, how to sit, when to measure, how many readings to take and how to write them down. Every number has its source at the bottom of the page.

This guide explains how to measure, not how to interpret the values. Only your doctor can tell you what your numbers mean: if you have doubts or symptoms, talk to your doctor.

Why your doctor asks for home readings

At the clinic your blood pressure is measured only a few times, in a setting that can make you tense. Readings taken at home, with a precise method and over several days, give the doctor a wider picture: this is why the European ESH 2023 guidelines see them as a complement to office readings.

How many days, how many times and at what hours is up to your doctor. The steps below are the general ones from the guidelines: if your doctor gave you a different schedule, follow theirs.

The right monitor

Use a clinically validated automatic upper-arm monitor (ESH 2021, American Heart Association). The list of validated models is published by STRIDE BP.
The ESH 2021 guidelines do not recommend wrist monitors and say that cuffless devices should not be used to measure blood pressure.
The cuff must be the right size for your arm, according to the monitor's instructions (ESH 2021). A cuff that is too small or too large distorts the reading.

In the 30 minutes before

No smoking, caffeine, meals or exercise in the 30 minutes before measuring (ESH 2021, American Heart Association).
Empty your bladder first: a full bladder affects the reading (American Heart Association).
Sit down and rest quietly: 3 to 5 minutes according to ESH 2021, at least 5 minutes according to the American Heart Association.

How to sit and where to place the cuff

Back supported by the chair, legs uncrossed, feet flat on the floor (ESH 2021).
Bare arm resting on the table, with the middle of the upper arm at heart level (ESH 2021, American Heart Association). Do not measure over your sleeve.
The lower edge of the cuff goes 2 to 3 cm above the bend of the elbow (ESH 2021).
Do not talk and stay still during the measurement (ESH 2021, American Heart Association).

Which arm to use is for your doctor to decide: at the first visit ESH 2021 recommends measuring both arms. At home always write down which arm you used, so whoever reads the diary knows.

When to measure and how many readings to take

For 7 days, and never fewer than 3, before the visit (ESH 2021, ESH 2023).
Twice a day: in the morning, before taking your medicines and before eating, and in the evening (ESH 2021, ESH 2023).
Each time, take two readings 1 minute apart (ESH 2021, ESH 2023, American Heart Association, NHS).
Try to measure at about the same time every day (American Heart Association).

The NHS reminds you that your doctor tells you for how many days: if your schedule is different, theirs is the one that counts.

Write everything down, discard nothing

Write down every reading exactly as the monitor shows it, without rounding and without leaving out the ones that look odd: the average is worked out by the doctor, or the app, on all readings. Next to the numbers note the time, the arm, the position and the context, for example if you had just had a coffee or had not yet taken your medicine.

ESH 2021 prefers monitors that store and average the readings on their own; otherwise it suggests a logbook. With Pediary each measurement collects the readings you add, and the app calculates the average blood pressure over all of them, without judging it.

What happens next

According to ESH 2021 the doctor looks at the average of at least 12 readings taken over at least 3 days, usually leaving out the first day. It is a calculation the doctor makes on your readings: this guide gives no thresholds and does not say when a value is high or low.

The World Health Organization points out that an evaluation by a health professional is important. Do not change your medicines based on the numbers you see at home: if you have doubts, or do not feel well, talk to your doctor.

A diary that does the maths for you

With Pediary's blood pressure diary you add readings as you measure, note arm, position and context, and bring your cardiologist a PDF with the averages. No colours and no judgement on the values.

Discover the blood pressure diary