A blood pressure machine is worth having for one reason. It produces readings your doctor can act on. The one that does this copies the surgery's setup, an inflatable cuff wrapped around the upper arm and a small machine that shows the numbers. [1]
The next step depends on where you stand. If a doctor or nurse has asked you to check at home, they may lend you a machine and show you how to use it. If you buy your own, machines may be slightly different, so follow the instructions that come with yours. If you own nothing yet, start with a check at a pharmacy or your GP surgery. Many pharmacies offer free checks for people aged 40 or over. [1]
The machine worth having copies the surgery's setup
A check at the surgery usually takes a couple of minutes. You sit down, roll up your sleeve or take off long-sleeved clothing, stretch your arm out and rest it on a table. An inflatable armband, the cuff, wraps around your upper arm and fills with air, which can feel uncomfortable for a few seconds until the air releases. Devices differ, but the armband is usually connected to a small machine that shows your blood pressure measurements. The test may be done a couple of times to make sure the measurement is accurate. [1]
The checks follow from it. Buy a machine whose cuff wraps the upper arm. Try the fit with your own fingers once the cuff is on. Read the manual before your first reading, since the NHS notes machines may be slightly different and tells buyers to follow the instructions for recording their readings. [1] On the question of choosing between monitors, NHS guidance points readers to the British Heart Foundation. [1]
The two-finger fit decides whether the number holds
The British Heart Foundation's senior cardiac nurse Ruth Goss sets out ten steps for taking an accurate blood pressure reading at home. These are the first five. [2]
- Wait until you feel calm and unstressed, and take off any thick jumper or cardigan, since heavy clothing affects the accuracy of the result. [2]
- Sit upright with your back against the back of the chair and your feet flat on the floor. [2]
- Rest your arm on a table, hand relaxed, and do not clench your fist while the machine runs. [2]
- Place the cuff over your upper arm with the tubing leading down the centre or slightly to the right of your arm. [2]
- Tighten the cuff until it is snug and you can still fit 2 fingers underneath. If two fingers will not slide in, the cuff fails the check. [2]
Home numbers meet a lower bar than clinic numbers
A reading carries two numbers. The first, the systolic pressure, marks the highest level your blood pressure reaches when the heart pumps blood around the body. The second, the diastolic pressure, marks the lowest level between heartbeats. [1]
The NHS guidance, last reviewed in November 2025, gives two thresholds. A reading is usually considered high at 140/90 or higher when a healthcare professional does the checking, and at 135/85 or higher when it is checked at home. [1] As an illustrative example, a home reading of 138/86 sits above the home bar while staying below the clinic bar. The same numbers change their meaning with the room they were taken in. Where your own readings fall is a conversation for your care team.
This is where the log comes in. When a check suggests blood pressure might be high, the surgery may ask you to use a monitor at home to check your blood pressure regularly over the next few days. [3] Take your blood pressure, make a note of the numbers, wait 1 minute and do it again. You usually do this twice, once in the morning and once in the evening, for as many days as your doctor or nurse tells you. [1]
The first real reading may cost nothing
Nothing here requires buying first. You can have your blood pressure checked at most pharmacies, at your GP surgery and at some workplaces. Some pharmacies may charge for a check. Many pharmacies offer free checks for people aged 40 or over. [1] The British Heart Foundation adds the England detail, free at some pharmacies there if you are over 40 and do not already have diagnosed high blood pressure. [2]
If your blood pressure needs to be monitored for 24 hours, you may be given a monitor to wear at home. You need to go to a GP surgery, health centre or hospital to have it put on and to return it the next day. Wearing it at home will not affect your daily activities. [1]
The reason for the routine is the condition itself. High blood pressure does not usually have any symptoms, and the only way to find out if you have it is to get it checked. [1] The British Heart Foundation links it to around half of all heart attacks and strokes in the UK, and counts around 5 million people living with it without knowing it. [2]
A machine that copies the surgery's setup and a log kept morning and evening hand your care team several properly taken measurements across several days. Those are the numbers worth carrying to your next appointment.