What is another word for ballpark figure?
Pronunciation: [bˈɔːlpɑːk fˈɪɡə] (IPA) 
When we are referring to an estimate or an approximation of a numerical value, we often use the term "ballpark figure". Nonetheless, there are several alternative expressions that we can use to convey a similar meaning. Some synonyms that we can use when we want to describe a rough estimate or an approximate figure include "rough idea", "guesstimate", "rough estimate", "ballpark estimate", "rule of thumb", "approximation", and "rough calculation". All these expressions are commonly used in both personal and professional contexts when there is a need to provide approximate figures without precise values. No matter which term we use, we must remember that these expressions always mean that the figure we are referring to may not be fully accurate and should be taken as an approximation.
