Taylor Swift is planning a tour announcement and ticket sale around her December birthday, Billboard has learned.

The pop icon has targeted Dec. 13, her 28th birthday, as a key date for selling tickets to her 2018 trek in support of her Reputation album, which is on track to sell at least 1 million units in its first week. 

Few details about the 2018 trek are known, although most expect the Reputation World Tour to be one of the high-grossest tours of the year, playing 27 markets (according to the map on her site), all home to NFL teams (except Toronto and Columbus, Ohio). An NFL-stadium run wouldn't be unexpected since the buildings are available throughout the spring and summer and promoter Louis Messina, who promoted Swift's 1989 tour and is expected to promote the Reputation tour, has a long history of promoting concerts at NFL venues. Kenny Chesney's 2018 No Shoes Nation tour, which Messina is also promoting, is playing NFL stadiums on a tour stretching from April 21 to August 25. Swift and Chesney are playing 17 of the same markets in 2018. 

The reputation Tour will also be a big test of Ticketmaster's Verified Fan program, which is powering Taylor Swift Tix, a registration and rewards portal where Swift fans are encouraged to purchase Swift's music and merchandise, watch her videos and share her content on social media, all in an effort to improve their chances of scoring tickets to one of her concerts. Registration for Taylor Swift Tix ends Nov. 28 and will be followed by a tour announcement and then a ticket sale tied to the singer's birthday.

If her 2018 reputation Tour is comparable to her 2015 1989 World Tour, Swift could gross between $250 to $300 million. The big number came in part due to a number of blockbuster North American dates, including a $13.4 million two-show stop at MetLife Stadium East Rutherford, New Jersey, according to Billboard Boxscore. She also grossed $13.1 million with two shows at Levi's Stadium in Santa Clara, California, $12.5 million with two stadium shows at Gillette Stadium in Boston and $11.4 million at Soldier Field in Chicago. If Swift played two stadium shows in every market at an average of $5.5 million in attendance, she would gross $297 million.

Of course the prospect that it actually works out that way is small -- Taylor might only play single nights in some markets, or play a mix of arenas and stadiums. In Los Angeles, Swift could play Staples Center instead of the Rose Bowl or L.A. Coliseum. Since Swift has played 16 concerts at the downtown L.A. arena (breaking Madonna's record), grossing $8.9 million with five shows in 2015. During her stop in the Bay Area she might play Oracle Arena in Oakland or AT&T Park in San Francisco -- in September Messina told Amplify that artists would skip Levi Stadium in Santa Clara until it increased its curfew.

“No one is going to play a building with a 10 p.m. curfew," he said. "It would mean the headliner would have to play when its still light outside and that’s just not something anyone would agree to." 

Ultimately, total gross will be dictated by the size of the venues she plays, the number of shows at each stop and the price of tickets, which last tour capped out at $139.50. Last year Swift grossed $250.7 million on her 2015 tour in front of 2.3 million fans, earning the honors of top tour of the year. In 2016 she was bested by Beyonce, who's tour grossed $256.1 million according to Billboard Boxscore, and Bruce Springsteen who grossed $255.3 million.

Photo: Getty Images

Swifties, are you ready for it? iHeartRadio’s newest station, Taylor Swift reputation Radio, is playing every track from T-Swift’s new album along with her greatest hits. We’re talking about "Look What You Made Me Do," "...Ready For It?" "Gorgeous," and "Call It What You Want." It also features exclusive audio from iHeartRadio’s reputation Album Release Party, featuring never-before-heard snippets from Taylor Swift's Secret Session.