Ball Park Figure

Meaning:
A general idea of something; an estimate.

Example:
I’m not sure how much a flight to Bali would cost, but the website should give you a ball park figure.

Did you know?
This idiom originates from the game of baseball. The ball park has a set number of seats. On the day of the game, the commentator would estimate the number of people attending the game. That estimated figure became known as the ball park figure.