Regardless of its physical size, TV hardware manufacturers reserve space around the displayable area of the screen. This reserved space is known as overscan. The amount of space a TV uses as overscan varies across manufacturers. Make sure you design your content in a way that no text is placed in this area.
Although Android and Amazon Fire TV platforms provides a way for the user to adjust for television overscan in the settings, we recommend that you avoid placing important content within the outer 5% of any edge on the screen. All of your messages should be fully within the inner 90% (the safe zone) of the images.