How Monitors Work
This information is for educational purposes only and should not replace medical advice. Always talk to your healthcare provider for medical decisions.
Most Important Things to Know:
Blood pressure monitors stop blood flow for a few seconds. They measure when blood starts flowing again.
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The top number (systolic blood pressure):
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Shows the pressure when your heart beats
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This is when blood is pushed into your body
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Measures when flow happens during each beat
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The bottom number (diastolic blood pressure):
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Shows the pressure when your heart gets ready to beat again
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Measures when blood flow happens between heart beats
What You'll Learn on This Page:
See step-by-step how your monitor checks your blood pressure
Learn where to place the cuff for accurate readings
See where we got this information and find trusted sources
How Blood Pressure Monitors Work
Cuff Location
Your blood pressure monitor measures the main artery in your upper arm. This artery runs down the inside of your arm.
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The cuff goes on your upper arm because:
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The brachial artery is close to the surface here
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It's large enough to give a clear reading
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Wrist monitors work differently:
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A wrist monitor's sensor goes over the artery on the thumb side of your wrist
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This is the same artery you feel when checking your pulse
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The artery in your wrist is smaller than the one in your upper arm
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Because it's smaller and farther from your heart, readings might be less accurate


The arrow on the cuff goes on the front part of your bicep. This is where the artery is.
A wrist monitor's sensor goes over the artery on the thumb side of your wrist. You should be able to feel it.
Remember:Â
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The cuff needs to be the right size to get accurate readings.
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Place the cuff directly on your skin, not over clothing.
Resources We Used
Written by:
Last Updated: January 16, 2025
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Disclaimer: The information provided on this site is intended for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition.