The Grand Prix schedule for January 2018 to June 2018 has been released. The 2018 calendar year will mark the first time a single tournament organizer, ChannelFireball Events (CFB Events). The first half of 2018 has a focus on Team events, including Team Limited, Team Unified Modern. and Team Trios Constructed (the same format as Pro Tour 25th Anniversary). The Top 4 from Team Grand Prix between January 8 and May 27 will qualify for the 25th Anniversary Pro Tour. The feeder schedule for other Grand Prix will be determined at a later date.
The first half of the 2018 schedule also features three double Grand Prix Weekends. Seattle, Las Vegas, and Birmingham will all feature two separate Grand Prix, similar to Las Vegas 2017. There will be two more double Grand Prix weekends, one in North America and one in Japan, in the second half of 2018.
The complete first half schedule, from this article by Scott Larabee, can be found below. The article also details the breakdown of all Grand Prix for the year, including format and potential locations. All told 2018 will have 60 Grand Prix.