The word "ballpark" is used to describe a rough estimate or a guess. It means to come close to the actual number or value without being exact. Full definition
CEO of Ballparks of America Hamilton Chang talks about how Branson has become a baseball hub for kids around the country. (petergreenberg.com)
I don't recommend counting calories precisely — but it can be important for a lot of people starting out with eating more to keep at least ballpark figures in mind in order to make sure you eat enough. (paleoforwomen.com)
The 1 % GWP figure is in the same ballpark of estimates of what it would take to decarbonise the world's energy system. (planet3.org)