There are various synonyms for the phrase "you would not believe," which is commonly used to express surprise or disbelief. These include "unimaginable," "unthinkable," "inconceivable," "astonishing," "mind-boggling," "jaw-dropping," and "out of this world." Each of these words or phrases conveys the speaker's amazement and emphasizes the incredible nature of what they are describing. Whether you are telling a story about a shocking event or expressing your astonishment at a surprising fact, these synonyms for "you would not believe" can help you to communicate your emotions more precisely and effectively.