How to measure your blood pressure at home

Sit with your back supported and feet flat for five minutes, arm on a table at heart height, cuff on bare skin. Take two measurements a minute apart, morning and evening, for seven days, then average them.

One measurement doesn’t tell you much, but a week of them, taken the same way, gives you a number you and a doctor can act on. In one analysis of 163 people, a week of home measurements varied less than measurements taken in a clinic or with a 24-hour monitor (Warren 2010).

The setup

Do this every time, in this order.

1. Skip caffeine, smoking and exercise for at least 30 minutes. Empty your bladder.
2. Sit in a chair with your back supported and both feet flat. Keep your legs uncrossed. Rest for 5 minutes without talking.
3. Put the cuff on your bare upper arm. Rest that arm on a table with the cuff at heart height. Don’t hold your arm up yourself.
4. Stay still and silent. Don’t talk, and don’t use your phone or text.
5. Take two measurements, 1 to 2 minutes apart. Write down both, or log them right away.

What each mistake adds

The American Medical Association and Johns Hopkins published estimates of how far common setup errors can push a number. The estimates come from research on clinic measurements, and the effect varies from person to person. Nearly all of these push the number up, so they can make a normal blood pressure look like hypertension.

Cuff size

Researchers have tested cuff size more directly than any of the other mistakes. In a randomized crossover trial of 195 adults, a regular cuff gave a systolic number 4.8 mmHg too high in people who needed a large cuff, and about 19.5 mmHg too high in people who needed an extra large one. In people who needed a small cuff, it came out 3.6 mmHg too low (Ishigami 2023).

Measure around the middle of your upper arm, or use the cuff size tool.

Sizes on the box vary by maker, so match your arm against the range printed on the cuff.

Which arm

Measure both arms once, then use the arm with the higher number from then on. If the second arm comes out much lower, measure the first arm again, since pressure can settle as you sit. If the gap stays at 10 mmHg or more, tell your doctor, since the AHA statement calls a gap that size clinically significant.

The seven-day method

The American Heart Association has you measure for a week.

If you take a blood pressure medication, the morning pair goes before that dose, and you keep taking it as prescribed. Don’t skip a dose to get a measurement.

At the end, average every measurement. The home average tool does the math and gives you a sheet for your doctor. The full day-by-day version is the seven-day home week.

What the average means

Home numbers often run lower than clinic ones, so keep them apart and don’t average the two together. The chart shows every category, and the checker gives you one next step for your own numbers.

Which device

• Choose a validated upper-arm cuff. The AHA statement says many home devices on sale haven’t been validated. How to track lists models checked against validated lists.
• Be careful with wrist cuffs. Some are validated, but they’re hard to use accurately, because the device slips off the artery and your wrist has to stay at heart height.
• Check your cuff against the clinic’s. Take yours to a clinic visit and compare it with theirs.
• Don’t rely on a watch. Apple Watch can send a hypertension notification, and FDA documents show it caught 41.2 percent of people with hypertension in its clearance study. The FDA summary says that getting no notification doesn’t mean you don’t have hypertension. The feature is cleared for adults 22 and over who haven’t been diagnosed with hypertension before, and it doesn’t give a blood pressure number.

If your pulse is irregular

If you have atrial fibrillation, automatic cuffs give a valid systolic number, but the diastolic (the bottom number) is less accurate, according to the AHA statement. Ask your doctor how to measure and how many measurements to take.

How often after that

Repeat the week after you change something, when your doctor asks, or when a clinic number surprises you. Use the same cuff, arm and times, so you can compare one week with the next. See how to lower your blood pressure for what to test.

Keeping the record

With Gyroscope One, you can turn any device into a smart device with just an iPhone and the app.

Take a photo of the monitor. Your numbers land in your blood pressure trend, with no Bluetooth needed.

For which cuff to buy, see how to track your blood pressure.

When to call

• Chest pain, shortness of breath, back pain, weakness, numbness, vision change or trouble speaking: call emergency services, whatever the number.
• A systolic of 180 or higher, or a diastolic of 120 or higher, with none of these: rest five minutes and measure again. If it stays that high, call your doctor the same day.
• Pregnant: follow your care team’s schedule. After 20 weeks, call them if you get 140/90 or higher on two checks at least 4 hours apart. If you get 160/110 or higher, or a severe headache or vision change, get care right away.
• A home week averaging 130/80 or higher: book a visit and bring the sheet.