700 - 800mb-according to the technical information available at linux from scratch ver 3.0, before we can build our new linux system, we need to have an empty linux partition on which we can build our new system. i recommend a partition size of at least 750 mb. this gives enough space to store all the tarballs and to compile all packages without worrying about running out of the necessarytemporary disk space. but you probably want more space than that if you plan to use the lfs system as your primary linux system.