An average of 38.7 million viewers watched the London Games on Tuesday night, nearly 5 million more than watched on the comparable day four years ago in Beijing and almost 9 million more than tuned in on the first Tuesday night of the Athens Games in 2004.

Through five nights, including the opening ceremony, NBC is averaging 35.6 million viewers, more than any Summer Olympics from outside the United States since the 1976 Montreal Games.

The results are considerably better than NBC expected. In Comcast’s earnings call with analysts Wednesday, Steve Burke, NBC Universal’s chief executive, said that the company had projected ratings would fall 20 percent from Beijing compared with the first five days in London, but that they were up 9 percent.

He said the forecasts surmised that the tape-delayed prime-time broadcast’s ratings would suffer for not having the live gymnastics and Michael Phelps races that NBC had from Beijing.

NBC also thought its London ratings would be like those from Athens, but they are up 26 percent.

Burke predicted that instead of losing as much as $200 million on the London Games, NBC might break even. NBC lost $223 million on the 2010 Vancouver Winter Olympics soon after Comcast announced it was acquiring a controlling interest in NBC Universal from General Electric.