Difficulty Score: how it works

The headline score

Every marathon on MarathonsIreland is given a difficulty score between 0 and 10, where 0 is pancake-flat and cool, and 10 is a brutal mountain marathon in the heat. The score is a weighted average of five components that account for everything that actually slows a runner down.

The five components

Elevation (60%)

Total elevation gain across the course. Flat coastal marathons score below 2. Undulating city courses around 3–5. Hilly mountain marathons above 8.

Hill placement (15%)

Where the climbing happens. Hills in the final third cost far more than hills early on — Heartbreak Hill at mile 21 of the Dublin Marathon is the classic example.

Weather (10%)

Based on typical race-day temperature, wind, humidity and rain probability. Ideal is 8–12°C with low wind. A secondary factor — Irish weather varies but the terrain defines most Irish marathons far more than the conditions.

Course layout (10%)

Measures the structural difficulty of the route — how repetitive it is, how many direction changes it demands, and how much of the same terrain runners must cover repeatedly. Detected automatically from GPS data. A multi-lap coastal out-and-back scores higher than a single point-to-point route.

Altitude (5%)

Marathons above 1,500m lose a meaningful amount of aerobic capacity. Irish road marathons are at sea level and score 1.

What the score doesn't include

Crowd support, aesthetics, organisational quality, cutoff generosity, and logistics all matter — but they don't affect how hard it is to physically complete the race. We track those separately in the race page so you can weigh them yourself.

The score is also not a predictor of your personal finish time. It's a relative ranking of courses. Your own fitness, training and pacing decide your actual result.

Updates and feedback

The methodology is versioned. The current version is v1.0. If we improve the scoring we'll rebuild every score and publish the changes here. If you think a particular race's score is off, let us know — we take runner feedback seriously.

See the scores

Browse all marathons by difficulty →