Team spokesman Tim Gelt said X-rays revealed the stress fracture in McGee's left tibia on Sunday.
McGee has been chronically bothered by soreness in the tibia, the inner and typically larger of the two bones between the knee and the ankle.
Timofey Mozgov figures to get his first start of the season in McGee's place when the Nuggets play at Utah on Monday night. J.J. Hickson also could see his minutes increased in McGee's absence.
The Nuggets are off to a 1-4 start under new coach Brian Shaw, who replaced George Karl last summer.
