Why is my Amazfit T-Rex Ultra 2 heart rate measurement inaccurate?

Measurement inaccuracies are often caused by wearing the watch too loosely or placing it too close to the wrist joint. For the best results, wear the watch at least one finger's width away from your wrist bone and ensure the strap is comfortably snug. External factors like arm hair, tattoos, or excessive arm movement can also impact the sensor's precision.