The Colorado Half Marathon Calendar is a complete simplistic listing of half marathons in Colorado. Currently the Colorado half marathon schedule has 2026 Colorado half marathons and 2027 Colorado half marathons as they roll in. Colorado half marathons 2026 & Colorado half marathons 2027 also identify trail half marathons and walker friendly half marathons by a (T) symbol and a (W) symbol.  The (T) means it is a TRUE trail half marathon (off road, switchbacks, etc) and a (W) means it is truly "official walker friendly" requiring the half marathon to allow a minimum of 18:32 mile pace, minimum 4 hours for participants to finish the 13.1 mile distance.

The Colorado half marathon schedule of course features races such as Rock'n'Roll Denver Marathon and Rock'n'roll Denver Half marathon, along with a complete listing of Colorado half marathons, Denver half marathons, Ft. Collins half marathons, Colorado Springs half marathons, Boulder half marathons, Rocky Mountain half marathons, Vail half marathons, and many more half marathons in Colorado.

A half marathon is 13.1 miles (or in kilometers is a 21k). We understand sometimes there will be a slight margin of error up or down when runners run or walk any race distance, however our calendar only is a listing for true half marathons that do all they can to measure their course as an official half marathon 13.1 mile / 21k distance.  Races that are not 13.1 miles, we encourage not to call their race a 1/2 marathon to lessen confusion for runners & walkers looking to participate in a true 1/2 marathon distance. Some runners don't care, but you'd be surprised how many that do.