Weiner has previously claimed that he has a final "image" in mind but he has now released further details.
According to Grantland, the writer explained that the idea for the ending came to him "in the middle of last season".
"I always felt like it would be the experience of human life," he said. "And human life has a destination. It doesn't mean Don's going to die.
"What I'm looking for, and how I hope to end the show, is like... It's 2011. Don Draper would be 84 right now. I want to leave the show in a place where you have an idea of what it meant and how it's related to you."
Weiner admitted that he does not want to "wear out the welcome", adding: "I was 35 when I wrote the Mad Men pilot, 42 when I got to make it, and I'll be 50 when it goes off the air. So that's what you're going to get."
Weiner continued: "Do I know everything that's going to happen? No, I don't. But I just want it to be entertaining, and I want people to remember it fondly and not think it ended in a fart."
Mad Men is due to return for its fifth season on AMC in the US and on Sky Atlantic in the UK next year.
> Mad Men creator Matthew Weiner: 'AMC made me look greedy'