Check How to Measure Your Blood Pressure Accurately at Home

Is the home blood pressure threshold the same as at the hospital?

The KDCA's "Diagnosis of Hypertension" (April 2022) sets different criteria depending on where you measure.

Writing 135/85 does not mean both numbers have to be high. The split takes into account that readings at home are usually lower.

Don't diagnose yourself just because you hit a threshold. The first step is to show your doctor several readings taken the right way.

What should you do before measuring?

Here is what the KDCA National Health Information Portal says to do before measuring.

• Avoid smoking, caffeine, and alcohol for 30 minutes before measuring.
• Lean back against the chair and keep the soles of your feet on the floor. Start measuring after resting at least 5 minutes.
• Place the cuff so its center is at the same height as your heart.
• Position the bottom edge of the cuff about 3 cm from the crease on the inside of your elbow.

How many times a day, and when?

The KDCA's 2026 "Hypertension" material says to measure repeatedly at a consistent time of day. Splitting records into morning and evening is only one example of fixing the times, so confirm your own measuring schedule with your doctor. For repeat readings within one session, follow the 2022 guidance.

How should you keep a record?

The KDCA National Health Information Portal advises recording the date, time, blood pressure reading, and which arm you measured. A notebook or a phone note is enough, as long as you can show it right away at an appointment. If your record shows you used the same arm at the same time of day, your doctor can interpret the values more easily.

How do you work out the average?

Let's calculate with made-up records. If the first reading is 138/88 mmHg and the next is 134/84 mmHg, the systolic is (138+134)÷2=136 and the diastolic is (88+84)÷2=86. The average record is 136/86 mmHg, and this is an example, not actual measurements. In this example, the two values differ by 4 mmHg for both systolic and diastolic.

The source says to measure once more if the two values differ by 20 mmHg or more. It isn't a rule to throw out only the first value; it comes with the premise that the later readings have settled. If they stay unstable, don't decide arbitrarily which value to discard. Show your measurement records to your doctor.

Keep the average for each session along with the measuring conditions. Even when you compare them with the home threshold above, don't jump straight to a diagnosis or a medication change. Use them as material to discuss at your appointment.

What do people often miss?

Reading the KDCA guidance in reverse shows the common mistakes: measuring only once in a hurry while standing, measuring right after a cigarette or coffee, a cuff that is off heart level, and a different measuring time every day. All of these go against the guidance above on the 5-minute rest, the 30-minute restriction, cuff position, and a consistent time.

When should you contact a medical institution?

The KDCA's 2026 "Hypertension" material advises not to wait until your scheduled appointment when symptoms change or your blood pressure changes a lot. Don't change your medication on your own based on the records alone. This post organizes publicly available measurement guidance and does not replace an individual diagnosis.