GPX Race Plan — Hill-Adjusted Pacing & Fueling
Trail ultra or road marathon — drop in your race GPX and get a hill-adjusted pacing plan: elevation profile, per-kilometer target splits, heat correction from real weather, and fueling timing. Everything runs in your browser — your file never leaves your device.
| Km | Grade | Target pace | Cumulative | Fuel / water |
|---|
| At | Point | Take |
|---|
How the hill adjustment works
Each 100 m of the course is graded from your GPX elevation. We weight every segment by its metabolic cost using Minetti's energy-cost model, so climbs slow you down and descents speed you up automatically. Your goal time is then distributed across these weighted segments to give realistic per-kilometer targets.
How weather changes your plan
Using the start coordinates and date, we pull the apparent ("feels-like") temperature from Open-Meteo. Within ~16 days that's a real forecast; further out we fall back to a multi-year seasonal normal. Heat above ~15 °C adds a progressive pacing penalty and raises your fluid and sodium needs.
Limitations
- GPS elevation is noisy — D+ is smoothed but still device-dependent.
- Trail surface (rocks, mud, stairs) isn't in a GPX, so technical courses may be underestimated.
- Heat tolerance is personal; the penalty is an average trend, not a guarantee.
- Forecasts are reliable within ~16 days only — beyond that it's a seasonal normal, not a prediction.