The Marathon Green Score

Golfers have a course rating. Runners deserve one too. We publish the full methodology on purpose: an open rating is more credible than a black box.

What leads: four separate questions, not one number

A single blended score hid the fact that a race can be easy to run but hard to enter (Boston), or a great debut but a long trip. So the headline on every race is now four independent dimensions:

Best for — the goal it serves best (first marathon, BQ course, bucket-list Major).
Course difficulty — how hard it is to run: terrain + typical race-day conditions only.
Planning friction — how hard it is to get into and get to: entry odds, travel, cost.
Data confidence — how much to trust our figures: verification status and data coverage.

The five axes below still power those dimensions, and the blended Green Score (1–10, 10 = easiest) is retained as a legacy general-purpose number — it just no longer leads.

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

Race-day climate is measured at each race’s start line and start hour, from one of two sources depending on the race: a 10-year Open-Meteo historical archive, or NOAA 1991–2020 climate normals. Each race page names which one it uses. Temperature and dew point drive our heat-adjustment; we do not currently surface historical wind, because the archive values we hold read as gusts rather than sustained race-morning wind and we won’t publish a number we can’t stand behind. Elevation, field size, fees, and entry paths are curated from official race sources; each race records the source URL and the date it was verified. Qualifying standards come from the BAA (Boston) and NYRR (NYC). We refresh seasonally as race calendars publish.

See it in action across the major US marathons and halves.

Browse races by Green Score →