IMTUF 100 - Idaho Mountain Trail Ultra Festival

IMTUF 100 - Idaho Mountain Trail Ultra Festival is held in McCall, Idaho, on September 19–20, 2026. Two trail formats are on the program: the 100-mile starting on Saturday, September 19 at 6:00 a.m., and a 20-mile on Sunday, September 20 at 9:00 a.m. McCall sits in Idaho's mountains, and the name of the event, an acronym for Idaho Mountain Trail Ultra Festival, sets the tone.

The 100-mile is a mountain ultra for experienced runners, ideally with a prior 100K or 100-mile finish, comfortable with long climbs, night running and self-management over a day and a half. The 20-mile on Sunday is the accessible option: long enough to be a real mountain trail challenge, short enough for runners who have done a trail half marathon. For the 100, a 20-week plan with back-to-back long weekends, hiking practice and a crew or pacer plan is the standard approach. For the 20-mile, 12 weeks with weekly hill work and a long trail run will do.