If you are not getting any successful heart rate measurements, your heart rate data seems inaccurate, or if you get different results than you do with a heart rate monitor, perform the following steps:

1. Make sure your ScanWatch Light is properly positioned.
   
2. Make sure you wear your ScanWatch Light tightly enough. It shouldn't be able to move around your wrist.
   Note: You may notice inaccurate heart rate data if you wear a metal or leather wristband.
3. Make sure you've launched the continuous heart rate mode before starting your activity.
   It can take up to 20 seconds for the first heart rate measurement to be displayed on your watch.
4. Make sure the sensor below your watch emits a blinking green light when the watch display is on.
5. Make sure your watch is clean and your wrist is moisturized but not sweaty or overly wet. 
   Note: Excessively dry skin may result in repeated failed recordings. If necessary, wash and lightly dry off your hand before attempting a heart rate recording. You could also apply moisturizer to your hand to prevent dryness.  

To obtain the most accurate results please follow these guidelines:

• The ScanWatch Light should be worn tightly enough that the sensor on the back of the watch face touches your skin.
• Wear the watch 1 to 2 finger width away from your wrist bone.
• Use the wristband Withings provides with your watch.
• Make sure that your watch stays in place during exercise. If it moves around at all, tighten your band one notch.
• Make sure your band is secure, but not too tight. It should be comfortable and allow proper circulation.
• Make sure the watch is clean, so the green LEDs are not obstructed by dust or dirt.

Additional factors that can cause the heart rate to be measured inaccurately:

Skin perfusion

Skin perfusion, or how much blood is flowing through the skin, varies among individuals and according to the environment. In certain circumstances, the watch may not be able to provide an accurate heart rate measurement.

Skin and blood properties

The technology used by the watch is based on the light absorbed by your skin and blood. Any permanent or temporary changes to your skin, such as tattoos, sweat, or even hair on the wrist may affect the measurements.

Environment

Environmental factors may affect the ability of the watch to take an accurate measurement. For example, water may obstruct or modify the light dispersion, and cold weather may impact skin perfusion.

Motion

The watch needs to stay securely in place to provide a heart rate measurement. Activities that cause force to the wrist, such as boxing or volleyball, may not allow the watch to provide an accurate heart rate measurement.

Please note that because of the clenched position the wrist is flexed in when cycling, the heart rate measurements may have some inaccuracies.

You can position your ScanWatch Light on the lower part of your wrist. Note that we cannot guarantee the accuracy of the heart rate data, because the product is not aimed to be positioned on the lower part of your wrist.

If you still encounter issues, reach out to Customer Service by clicking the Contact us button at the bottom of the page.