Races Marathon · Boulder, USA
Boulderthon Marathon
Boulderthon Marathon is a rolling marathon in Boulder, USA, held each September. Starts at 19th and Pearl in downtown Boulder and finishes at 14th and Pearl. Mostly paved roads and multi-use paths with about 260 metres of total climbing. Late September mornings in Boulder are usually cool and dry, roughly 5 to 20°C over the race. Boulder's rolling course rewards effort-based pacing — hold steady effort on the rises and let the pace return on the descents.
Page rebuilt 2026-11-14 · race facts not independently verified — confirm dates and entries on the official race site
When
September
next: Sunday 26 September 2027
Course
rolling
Marathon
Conditions
Late September mornings in Boulder are usually cool and dry, roughly 5 to 20°C over the race.
Racing this course well
Starts at 19th and Pearl in downtown Boulder and finishes at 14th and Pearl. Mostly paved roads and multi-use paths with about 260 metres of total climbing.
Boulder's rolling course rewards effort-based pacing — hold steady effort on the rises and let the pace return on the descents.
Getting a place
Official Boulderthon Marathon site →Checked November 2026
Race day
- Next race
- Sunday 26 September 2027
- Start time
- 07:00
- Time limit
- 6 hours, timed from the last runner crossing the start line
- Pacers
- Pace groups at 3:30, 3:45, 4:00, 4:30, 5:00 and 5:30
- Also on the day
- half-marathon, 10k, 5k
The course in numbers
- Surface
- About 98% paved roads and paths, with a short packed gravel section
- Total climb
- 260 m (850 ft)
- Start altitude
- 1,625 m (5,330 ft)
- Course status
- USATF sanctioned, measured by a Level A USATF course measurer
- Boston qualifier
- Yes
Worth knowing
- Runners more than 10 minutes behind the pace limit can be moved to the 10K.
Getting there
- Nearest airport
- Denver International (DEN)
Pick your goal for Boulder
Pace charts, weekly structure and timelines for the most common marathon goals:
The date shown is the one the organiser has announced. Change it if yours differs.
Build your training around Boulderthon Marathon.
RunV works backwards from race day to today. Your plan adapts when life interrupts, and you approve every change. It does not adapt to this specific course — the pacing guidance above is where the course knowledge is.
Everything above stays free and complete — this is an optional next step, not a paywall.
Asked often
- When is the Boulderthon Marathon?
- The next Boulderthon Marathon is on Sunday 26 September 2027 in Boulder, USA. It is held each September.
- Is the Boulderthon Marathon course flat?
- Starts at 19th and Pearl in downtown Boulder and finishes at 14th and Pearl. Mostly paved roads and multi-use paths with about 260 metres of total climbing.
- Is the Boulderthon Marathon a Boston qualifier?
- Yes. The Boulderthon Marathon is run on a certified course, so a time set here can be used to apply for the Boston Marathon.
- How should I train for the Boulderthon Marathon?
- Match your preparation to Boulderthon Marathon's profile and the September weather, then protect consistency — with RunV Premium you can adapt your plan to fit your week, so one bad week never derails the block.
Not sure what to target? Predict your marathon time from a recent race →
More marathon races
Supplements research for this distance
Build for Boulder — around your actual life
RunV engineers your block backwards from race day in September — and adapts it when training doesn't go to script. You approve every change.
