1. You’ve told me about the down payment, the closing costs, the interest rate, and the price of the house. What’s the bottom line? How much money am I actually going to have to spend on this house?
2. You and I can argue around and around on this issue, but the bottom line is that our children will have to go to college if they want to get well-paid jobs in the future.

Synonyms: long and short of it , nitty-gritty. The expression is often used to describe a monetary figure (opt.1), but it also describes the basic, (supposedly) undeniable truth of an argument (opt.2). The expression probably originates from the accounting practice of adding together the profits and subtracting the costs to arrive at a final figure under the bottom line on a spreadsheet or in a ledger or account book.