Measuring up is often used to describe someone who meets expectations or standards. However, there are several antonyms for this phrase that could be used to describe someone who falls short. Some examples include failing to measure up, falling behind, falling short, not making the grade, and missing the mark. Each of these phrases conveys a sense of disappointment or inadequacy, which is the opposite of measuring up. When discussing someone who fails to meet expectations, it is important to choose the right antonym to convey the specific message or feeling.