The league salary cap is $56.7 million.
The Red Wings' $44.5 million figure includes eight defensemen, one goalie and 11 forwards for a total of 20 signed players. That leaves $12.2 million of cap room with a few more players to be signed.
Keep in mind that Henrik Zetterberg must and will be signed to a contract extension, so the Wings won't bump up to the cap this season. They'll add about $5 million or more to next season's cap total with Zetterberg's new contract kicks in. So the Wings have $7 million or less to play with in signing Filppula, Howard, Chelios and anyone else this season.
And keep in mind that the cap figure will vary depending on the roster. For example, my figure includes Darren Helm, but if he starts in Grand Rapids, the cap number changes.