Griffin is yet to feature for the Redskins in their warm-up campaign due to a knee injury that he suffered at the end of last season, although he has publicly stated that he has been ready to play.
However, coach Mike Shanahan has stuck to a rigid recovery schedule in order to assure that Griffin has the best chance to play in the opening match of the season, and the 23-year-old insists that he is now at least 100% fit.
"I would say I'm 100%, but you can't put a number on it," Griffin told ESPN.
"No-one ever knows when they are 100% or what percentage they're playing at. The biggest thing is, I'm not below 100%."
The Redskins will face the Tampa Bay Buccaneers in their final warm-up match on Thursday before hosting the Philadelphia Eagles on September 9.