The Marathon Green Score
Golfers have a course rating. Runners deserve one too. The Green Score is a single number from 1 to 10 (10 = easiest) that captures how hard a race is to run — and to get to — built from five axes. We publish the full methodology on purpose: an open rating is more credible than a black box.
Terrain 30% of composite
Total elevation gain normalized to feet per mile, with a penalty for any segment over ~100 ft/mi or 4% grade. Net-downhill courses are docked too — they shred quads as much as climbs.
Climate 30% of composite
The 10-year average race-day temperature and dew point at the start, combined into a heat-index proxy. Cool and dry scores high; hot and humid scores low.
Logistics 15% of composite
How hard it is to get in: open registration scores 10; lotteries scale by acceptance rate; qualifier-only and World Marathon Majors score lowest.
Travel 15% of composite
Great-circle distance from your home, bucketed local → drivable → short flight → international. (Cost is estimated separately.)
Field 10% of composite
Crowd support and pacing help — bigger fields and official pacers make finishing easier, especially for first-timers.
The composite
The headline Green Score weights the axes 0.30·Terrain + 0.30·Climate + 0.15·Logistics + 0.15·Travel + 0.10·Field. For first-timers we also compute a re-weighted score that leans on the things that actually decide whether you finish — 0.40·Terrain + 0.35·Climate + 0.15·Field + 0.10·Logistics — ignoring travel and entry difficulty.
Data sources
Climate comes from 10-year Open-Meteo historical normals at each race’s start location and hour. Elevation, field size, fees, and entry paths are curated from official race sources. Qualifying standards come from the BAA (Boston) and NYRR (NYC). We refresh seasonally as race calendars publish.
See it in action across every US marathon and half.
Browse races by Green Score →