Road running

Boulderthon Boulder Marathon

📅 September 26, 2027 (estimated date)📍 Boulder · United States

⚠️ 2027 edition: provisional information

The date is estimated from the 2026 edition (September 27, 2026), on the same day of the week. Courses, start times, fees and description are carried over from the previous edition: check them on the official website. This page will be updated as soon as the organizer publishes them.

Available distances

26.2 mi13.1 mi6.2 mi3.1 mi

About

The Boulderthon Boulder Marathon in Boulder, Colorado, offers a scenic and challenging day of running on September 26, 2027, with a full marathon (26.2 miles / 42.2 km), a half marathon (13.1 miles / 21.1 km), a 10K (6.2 miles) and a 5K (3.1 miles). The courses combine mountain views, rolling hills and Boulder's scenery, and are all designed to showcase the natural beauty of the area.

Runners pass Boulder's iconic Flatirons, take in sweeping mountain views and run along the Boulder Creek Path. With enthusiastic local crowds and a relaxed, laid-back atmosphere, the event celebrates Boulder's outdoor lifestyle.

D-343

Prepare for Boulderthon Boulder Marathon with RunRun

An AI-generated training plan, adjusted every week based on your real sessions. Built around your goal, current level and race date.

Personalized plan based on your VO2max, history and weekly availability
Strava and Garmin sync: your sessions are analyzed and the plan adapts
Target paces, long runs, key sessions: everything is calculated for race day

Create my free plan No credit card. Sign up in 30 seconds.

Races nearby

Other upcoming races around Boulder.