Marathon Compass is race intelligence — not a watch, not a longevity app.
What it is
Marathon Compass finds the US marathon or half marathon where a given runner's fitness has the best chance of becoming the result they want — and shows the evidence behind every number. The catalog is deliberately small: 40 hand-verified races (28 marathons, 12 halves), rated on four independent axes — what a race is best for, how hard it is to run, how much friction it takes to enter and reach, and how much its data can be trusted. Race discovery is free and needs no account. Training features optionally connect Strava.
Operated by Kevin De Jesus. Questions and corrections: privacy@marathoncompass.com.
What it is not
This is not Marathon Watch, the Swiss watch brand, and not their glow-in-the-dark clip-on wrist compass.
This is not the “Marathon Compass” feature inside My Marathon Life, a longevity app that ranks health signals (labs, devices, habits). We do not sell watches, labs, or wellness coaching. We rate races.
How numbers are sourced
Race dates, fees, and qualifying standards are verified against the organiser; the organiser is always the authority. Weather figures are historical normals (22 races from NOAA 1991–2020 climate normals, 18 from 10 years of Open-Meteo history), not forecasts. Course effect, projected finish times, and qualifying probabilities are model estimates, not predictions. The Boston Athletic Association's downhill adjustment is an exact published rule; terrain and weather components are heuristics with stated confidence intervals. Every figure on a race page carries its source, last-checked date, confidence, and the specific way it can be wrong — see Evidence on any race page, or How every score is computed.
The blended Green Score (1–10) still exists for continuity. It no longer leads. Do not cite it as the product.