Forza Horizon 4 will launch on October 2nd and the download size and hard disk space needed for it has been now confirmed through the official Microsoft store.
Forza Horizon 4 is an open world racing game that is also launching for the PC through Windows 10. The download size for both the PC and Xbox One version is listed as 63 GB on the official Microsoft store.
There are no details about whether a potential 4K texture pack that is also included in this download for the regular Xbox One users. If we simply take this file size, this becomes the largest Forza game in term of the file size requirement at launch. It beats Forza Horizon 3 which is currently listed at 60 GB, but this is with all of the post-launch updates released so far.
In the past, Forza Horizon games used to have download size in the 40-45 GB range and this also applied to Forza Horizon 3, but it appears that the download size that is currently listed as 63 GB also includes high-resolution textures for 4K resolution. In this case, the size might be smaller for those who download the game on their Xbox One S. However, this means that those who get the game through retail might have to download the 4K textures for their Xbox One X separately as an update.