The antonyms for the word "official formula" may vary greatly depending on the context. However, some possible antonyms could be "unofficial method," "informal approach," "improvised formula," or "untested solution." These terms suggest a lack of formality, structure, or authority in contrast to the "official formula," which usually implies a well-established and widely accepted method or process. Additionally, words like "unconventional," "experimental," or "unorthodox" could also describe an antonym of the official formula, implying a rejection of traditional or recognized approaches in favor of new and innovative methods. Ultimately, the antonyms of "official formula" may convey different meanings depending on the situation, but they often suggest an alternative or non-standard approach.