Here are the specifications for a typical 1×4 hdmi splitter that supports 4k resolution:
input/output:
1 hdmi input
4 hdmi outputs
resolution:
supports up to 4k (3840x2160) with ycbcr 4:4:4 chroma subsampling12.
bandwidth:
18gbps video bandwidth.
compliance:
hdmi 2.0b and hdcp 2.2 compliant
audio support:
lpcm 7.1, dolby truehd, and dts-hd master audio
additional features:
edid management with dip switch for different presets
auto downscaling feature to support both 4k and 1080p displays simultaneously
compact design and plug-and-play setup