The Hardest Marathons in the World

How this ranking is calculated

Every marathon here is scored by the same model, so the comparison is like-for-like. For each course we take its total elevation gain, its net descent, its surface (road, mixed or trail) and the typical temperature on its race date, then compute how many minutes that combination adds - or saves - versus a flat, cool road marathon run at the same effort. That figure is the “vs flat road” number in the table above: +12 min means the course should cost a middle-of-the-pack runner about twelve minutes.

The factors compound. A course with both a big climb and race-day heat is far harder than one with either alone, and sustained trail sections slow most runners by 10-20% on top of the elevation. Because the score depends only on the course and its weather - never on who is running - it ranks every marathon on one honest scale.

Full method and worked examples are on the difficulty methodology page. To see the exact time a given course would add to your goal pace, use the marathon difficulty calculator.