Look around yourself and you'll see a lot of people wearing smartwatches. These devices have made it easier to track several aspects of health, from heart rate and sleep patterns to physical activity. Some newer wearable devices also claim to measure blood pressure, allowing users to check their readings without visiting a clinic. People who are concerned about their blood pressure levels, this feature may seem useful. However, just because a smartwatch displays a blood pressure number does not mean it is as reliable as a conventional blood pressure monitor.

Blood pressure readings help doctors assess how hard blood pushes against the walls of the arteries. Consistently high readings can increase the risk of heart disease, stroke and kidney problems. This is why accuracy is important when monitoring blood pressure at home. While smartwatches are convenient, their technology and methods of measurement can differ from those of medical devices. Understanding these differences can help you decide whether to trust the numbers on your wrist or use a blood pressure monitor instead.

How Do Smartwatches Measure Blood Pressure?

Most conventional blood pressure monitors use an inflatable cuff that tightens around the upper arm or wrist. The device detects changes in blood flow as the cuff inflates and deflates, calculating systolic blood pressure, the pressure when the heart contracts, and diastolic blood pressure, the pressure when the heart relaxes.

On the other hand, smartwatches use different methods, depending on the model. Many of these use optical sensors that shine light into the skin to detect changes in blood volume. Some devices combine these signals with information about pulse patterns and other measurements to estimate blood pressure using algorithms.

Can You Trust Smartwatch Blood Pressure Readings?

Not always as the accuracy of a smartwatch depends on its technology, design, calibration and whether it has been properly tested for blood pressure measurement. A device that estimates blood pressure trends may not provide an accurate reading for diagnosing hypertension.

The American Heart Association's 2025 scientific statement highlights concerns about the reliability of cuffless devices in everyday conditions. Their performance can vary during movement, sleep and physical activity, as well as with changes in body position and the time elapsed since calibration.

Therefore, a smartwatch reading should not automatically be treated as a reliable medical measurement.

Smartwatch Vs Traditional BP Monitor: Key Differences

  • Method of measurement: A conventional upper-arm monitor uses an inflatable cuff to measure blood pressure. Most cuffless smartwatches estimate it indirectly using sensors and algorithms.
  • Accuracy: Upper-arm monitors are generally preferred for home monitoring. Smartwatch accuracy varies by device, and many models lack sufficient evidence to support medical use.
  • Convenience: Smartwatches are easy to wear throughout the day and may offer frequent estimates. Traditional monitors need users to stop and take a measurement.
  • Medical use: A validated cuff-based monitor is suitable for tracking blood pressure at home and sharing readings with a doctor. A smartwatch should not replace it unless the specific device has been validated and authorised for the intended use.

What Can Affect Smartwatch BP Readings?

Several factors can influence the accuracy of wearable measurements:

  • Incorrect positioning: The position of the wrist and arm can affect sensor readings. Movement during measurement may also interfere with the results.
  • Calibration issues: Some devices require periodic calibration against a conventional blood pressure monitor. If calibration is outdated or inaccurate, subsequent readings may become less reliable.
  • Skin and sensor contact: Poor contact between the watch and skin can affect the signals collected by optical sensors.
  • Changes in the body: Exercise, changes in blood flow, medication and other physiological factors can impact readings. A device may not accurately capture these changes in every situation.

How To Check Your Blood Pressure Accurately At Home

The American Heart Association recommends using a validated automatic monitor with an upper-arm cuff. Follow these steps to improve accuracy:

  • Avoid smoking, exercise and caffeinated drinks for at least 30 minutes before measuring your blood pressure
  • Empty your bladder and sit quietly for five minutes before taking a reading
  • Sit with your back supported, feet flat on the floor and legs uncrossed
  • Place the cuff on your bare upper arm and support your arm at heart level
  • Take two readings at least one minute apart and record both results
  • Measure at consistent times and share the readings with your doctor when required

When Should You See A Doctor?

Do not rely on a smartwatch alone if you suspect you have high blood pressure, have already been diagnosed with hypertension or are taking medication to control it. Use an appropriate validated monitor and discuss your readings with your doctor.

However, if your smartwatch repeatedly reports unusually high or low readings, confirm them using a reliable blood pressure monitor. Do not start, stop or change medication based on smartwatch readings without medical advice.

A blood pressure reading above 180/120 mm Hg needs immediate attention. If it remains this high when checked again, speak to a doctor immediately.

Disclaimer: This content including advice provides generic information only. It is in no way a substitute for a qualified medical opinion. Always consult a specialist or your own doctor for more information. NDTV does not claim responsibility for this information.