How long of an HDMI cable will cause signal loss?

For ordinary copper-core HDMI cables, signal attenuation begins to occur after 3 meters. Within 15 meters, the signal quality can remain relatively high. Beyond 15 meters, the signal quality gradually declines. The maximum transmission distance is usually no more than 30 meters; otherwise, the signal will be severely lost, affecting the display quality of audio and video.

Signal performance at different distances

• 3 meters or less: Within this distance, the ordinary copper-core HDMI cable generally does not have significant signal attenuation issues, and can stably transmit audio and video signals, ensuring the clarity of the picture and the fidelity of the sound. It is suitable for most home entertainment scenarios, such as connecting televisions with set-top boxes, game consoles, and other devices.
• 3 - 15 meters: Starting from 3 meters, the signal will gradually experience a certain degree of attenuation. However, within the transmission distance of 15 meters or less, through reasonable design and manufacturing processes, the HDMI cable can still maintain a relatively high signal quality. Nevertheless, as the distance increases, the degree of signal attenuation will gradually increase, and there may be slight degradation in picture quality or sound distortion, but generally, it will not have a significant impact on the normal viewing and listening experience.
• Over 15 meters: When the transmission distance exceeds 15 meters, the signal quality will decline more significantly. At this time, problems such as flickering pictures, color distortion, and intermittent sound may occur, seriously affecting the display quality of audio and video.

The maximum reliable transmission distance in accordance with the HDMI 2.0/2.1 standard
Under the condition of complying with the HDMI 2.0/2.1 standard, the maximum reliable transmission distance without repeaters is 30 meters. This means that if using HDMI cables that comply with these standards, within a distance of 30 meters, theoretically, the signal can be stably transmitted without severe signal loss problems. However, once this length is exceeded, signal attenuation will become very severe, causing a significant decline in the stability of picture and sound transmission, and may result in screen freezing, screen distortion, sound interruption, and other situations, seriously affecting the user experience.