The 35-year-old has worked this offseason with quarterback coach George Whitfield, who helped train 2011 No. 1 overall pick Cam Newton, and dropped 15-20 pounds. He estimated in an interview with NBC SportsTalk that there's an "80 to 90 percent" chance that he'll be on a team by September.
"I have about three teams that I'm looking at," McNabb said.
The third overall pick in 1999, McNabb has been jettisoned by three teams in the past two seasons. He was dealt from the Eagles to the Redskins in 2010 and started 13 games but had 15 interceptions and 14 touchdowns, was publicly criticized by coach Mike Shanahan and landed with the Vikings. He started only six games before rookie Christian Ponder was inserted as the starter in Minnesota.
McNabb does accept that he'll likely only return to the NFL in a backup capacity.
He wasn't signed when the Vikings released him last season despite several teams -- including Chicago, Dallas and Kansas City -- facing injury questions at the quarterback position.
"I think teams are looking at what they have. They're evaluating their young quarterbacks, their backup situation," McNabb said. "Obviously, their starters they feel very confident in, but if things were to go wrong in training camp, or maybe the competition isn't where they need it to be, they'll obviously pick up the phone and call."