It's part of, as he told CNN's Wolf Blitzer on "The Situation Room" in his first interview since announcing his bid, his emphasis on "becoming internationalist as a country."
"This is just one piece, as I said, of becoming internationalist as a country and getting away from that unilateralist approach, that muscular approach to the world, that I don't think is working in our best interests," he said.
Chafee added that it would be "good for our economy, bottom line."
During his announcement earlier Wednesday at George Mason University in Virginia, Chafee announced his intention to "wage peace," and also issued his call to switch measurement systems.
"Let's be bold -- let's join the rest of the world and go metric," he said during his launch. He clarified during a question-and-answer session after that it would be a "symbolic integration" meant to show goodwill to the world.
He acknowledged that shifting to the metric system could cost the U.S., but that "the economic benefits that would come in would surpass those costs of putting up new signs and the like."
During his interview on CNN, Chafee also proposed "reinvigorating" the United Nations as part of his solution to the threat posed by ISIS.
"We have to work collectively, work with all our nations around the world" to combat terrorism, he told Blitzer.
He said ISIS was on the rise due to the Iraq War, and for that reason Hillary Clinton's vote for the war was disqualifying. And Chafee refused to say, when asked twice, whether he would vote for Clinton if she wins the Democratic nomination, as expected.
"We'll cross that bridge if we come to it," Chafee said with a smile. "Considering all the issues that are occurring, I'm not convinced she's going to be the Democratic nominee."
But the former Rhode Island governor declined to offer much more by way of details on his plan to combat ISIS.
"We're still learning exactly what's occurring" with the militant radical group that's known to behead and burn foreigners alive.