What do blood pressure numbers mean?

Originally Published: October 5, 1995 - Last Updated / Reviewed On: July 1, 2010
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What does a large split in blood pressure numbers mean? For example, a 26 year old male with a reading of 143/73.



Dear Pumping,

With all the health recommendations out there, it's tough to keep the numbers straight. The cutoff point or "magic number" to remember for normal blood pressure is 120/80. It's not really important how far apart the two numbers are, but whether or not each one is within the healthy range.

The first number of a blood pressure reading is the systolic pressure, when the heart is pumping. The second or bottom number is the diastolic blood pressure, when the heart is relaxed between beats. The units, mmHg, simply stand for millimeters of mercury. According to the National Heart Lung and Blood Institute (NHLB), healthy adults over age 18 should have a blood pressure measurement that's less than 120/80. If your systolic measurement is over 120 mm Hg or your diastolic measurement is over 80 mm Hg, then you have an increased risk of high blood pressure, also known as HPB or hypertension. This chart from the NHLB summarizes the different blood pressure categories:


Systolic in mmHg
(top number)


Diastolic in mmHg
(bottom number)


Less than 120


Less than 80


120 to 139


80 to 89

Stage 1 HBP

140 to 159


90 to 99

Stage 2 HBP

160 or higher


100 or higher

In your example, a measurement of 143/73 falls in the category of Stage 1 HPB. However, this isn't necessarily cause for alarm. Blood pressure readings vary depending on factors such as stress, excitement, anxiety, and setting. Therefore, health professionals recommend that you calculate your blood pressure from an average of three readings on separate days. Since you only gave one example for a 26 year-old man, it's impossible to determine if you have HPB or if you just got an inaccurate reading. For a more precise picture of your health, get a few more readings and then ask your provider if your results show the possibility of a problem with hypertension.

Approximately 95 percent of hypertension cases come from unknown causes, but most tend to involve many factors, including diet, obesity, alcohol abuse, physical and emotional stress, environment, and psychological and genetic factors. Most of the factors can be altered, which is how people are able to lower their blood pressure with advice from a health professional and some lifestyle changes.

For some more information on hypertension and blood pressure, check out the related Q&As. To discuss your blood pressure with a clinician at Columbia's Primary Care Medical Services log on to Open Communicator or call x4-2284 for an appointment. You may find more specific information about hypertension from the Mayo Clinic.

Here's to keeping your heart healthy, whether you're pumping iron or pumping up a blood pressure cuff.