Dad Brad admitted to Oprah Winfrey today that he's the happiest he's ever been -- but is Pitt ready to take on all six kids at one time?

That's false. The proud papa beamed when talking about the Brangie bunch, but confesses that he can't care for all six kids on his own -- just yet. "Four is usually my limit on my own so far," the actor tells Oprah. "I hope to advance to six."

Brad's latest flick, "The Curious Case of Benjamin Button," hits theatres Christmas Day.