HandBrake

Description of problem or question:
Hello everyone. I'd like to convert a x265 video to x264 but I have a question regarding what bitrate the x264 video should have.
For example, let's say that we have a 1080p x265 video encoded at ~2000 kbps average bitrate.
When I convert the video to x264, what should the bitrate be so that video quality matches the one of the x265 video?
If the x264 result video also has 2000 kbps avg bitrate, is the video quality almost identical or significantly worse than the x265 file? HEVC is able to maintain good-excellent quality at low bitrate but H.264 can't, so what happens when I encode to x264 at same bitrate? As far as I know I can't/shouldn't convert to x264 at higher bitrate because you can't increase bitrate out of knowhere without the original 10000+ kbps video.

There's no such formula, and even speaking loosely it would depend on a great number of factors in the encoding settings. Your premise that x264 can't maintain good-excellent quality at low bitrate is mistaken to say the least.

Quality based encoding is recommended here, as always. Pick a reasonable RF target and see how it works for your specific content and preferences.

ok, thanks. I'll try with CRF values.