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.
D+ is a smoothed estimate from your GPX's device elevation (sampled every 100 m). Organizer or DEM figures (e.g. ASTER) can differ by 10–30%.
| 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.
FAQ
- How does this adjust pace for hills?
- It scores every segment's slope with the Minetti energy-cost curve, so climbs are paced slower and descents faster while holding your target finish time. Climbs steeper than about 20% are capped to a power-hike pace.
- Does it account for heat?
- Yes. When the forecast or climate-normal apparent temperature is above 15°C it applies a progressive slowdown (larger past 25°C and 30°C) and raises fluid and sodium targets.
- Is my GPX file uploaded anywhere?
- No. Your file is parsed locally in your browser and never leaves your device.