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Blood pressure — norms and how to interpret them

What systolic and diastolic values mean, what the blood pressure norms are and when we talk about hypertension. A practical guide with a table of norms.

Blood pressure is one of the basic indicators of cardiovascular health. Regular measurements allow early detection of hypertension, which for years may give no symptoms at all. In this guide we explain what the two numbers on a blood pressure monitor mean and how to read whether the result is normal.

What do the two numbers mean?

A measurement is recorded as two values, for example 120/80 mmHg:

  • Systolic pressure (the first, higher number) — the pressure in the arteries at the moment the heart contracts, when it pumps blood.
  • Diastolic pressure (the second, lower number) — the pressure between heartbeats, in the relaxation phase of the heart.

The unit is the millimetre of mercury (mmHg).

Blood pressure norms

The most commonly used classification for adults is as follows:

  • Optimal: below 120 and below 80 mmHg.
  • Normal: 120–129 and/or 80–84 mmHg.
  • High-normal: 130–139 and/or 85–89 mmHg.
  • Grade 1 hypertension: 140–159 and/or 90–99 mmHg.
  • Grade 2 hypertension: 160–179 and/or 100–109 mmHg.
  • Grade 3 hypertension: at least 180 and/or at least 110 mmHg.

Pressure that is too low (hypotension) is usually spoken of at values below 90/60 mmHg, when accompanied by symptoms.

How to read an ambiguous result?

If one number falls into a different range than the other, the one indicating the higher category is taken for classification. Example: a result of 135/95 mmHg — the systolic value of 135 corresponds to high-normal, but the diastolic value of 95 is already grade 1 hypertension, so we classify the whole result as grade 1 hypertension.

How to measure blood pressure correctly?

  1. Rest for 5 minutes in a seated position before measuring.
  2. Do not drink coffee or smoke cigarettes for half an hour before the test.
  3. Support your back, do not cross your legs, and rest your arm at heart level.
  4. Take two measurements 1–2 minutes apart and record the average.

Why is hypertension dangerous?

Untreated hypertension increases the risk of heart attack, stroke, kidney failure and other complications. Because it gives no symptoms for a long time, it is sometimes called the silent killer. That is why even people who feel well should check their blood pressure periodically.

A single raised measurement does not yet mean disease — a diagnosis of hypertension is made by a doctor on the basis of several measurements. This article is for information only and does not replace medical consultation. If your results are abnormal, contact a doctor.

Check which range your result falls into: Blood pressure calculator →