When describing something as "off the charts," we mean that it is exceptionally outstanding or extreme in some way. Some synonyms for this phrase include "unprecedented," "astounding," "exceptional," "extraordinary," "phenomenal," "remarkable," "unbelievable," and "unmatched." Another way to phrase this could be "off the scales," which implies that the level of something is so high that it exceeds what was once thought possible. Whatever word choice is made, using descriptive language that can accurately convey the impressiveness of something is crucial to effectively communicate its impact or significance.