Ballpark figure
A ballpark figure is a rough estimate used to provide a general idea of a quantity or value, especially when precise data isn't available. It's helpful for simplifying discussions and providing a starting point for planning. However, relying too heavily on a ballpark figure can be perilous in situations requiring accuracy, particularly when data is sparse. While useful, it should be supplemented with more accurate information when possible to avoid misunderstandings or flawed decisions.