"Let's call it a day" is a common phrase used at the end of a long day of work or an activity. However, there are other ways to express the same sentiment. Some synonyms for this expression include "let's pack it in," "let's wrap it up," "let's end it here," "let's finish for now," and "let's put a pin in it." These phrases all convey the idea that it's time to stop what you're doing and move on to something else. Using synonyms can help add variety to your language and prevent repetition, making your conversations more engaging and interesting.