The antonyms for the phrase "guesses at" can vary depending on the context. However, some common words that can be used as antonyms for "guesses at" include "knows," "ascertains," "determines," "confirms," "verifies," "calculates," "proves," and "establishes." These words indicate a level of certainty or accuracy, unlike "guesses at," which suggests a subjective, uncertain attempt to predict or interpret something. Hence, if you want to communicate precision and confidence in your language, using any of these antonyms can help you convey the intended meaning more clearly.