GPX Explorer
Upload your GPX file and explore your route on a 3D terrain map — completely free, no account needed.
- Fly through your route in 3D with real satellite imagery and terrain data.
- See real difficulty numbers — total climb, descent, and km-effort.
- Inspect the steepest sections and the high point on the elevation profile.
Drag your GPX file here
.gpx files supported
Your file never leaves your browser — nothing is uploaded anywhere, it's processed entirely on your device.
How the Stats Are Calculated
Km-Effort
Based on the ITRA (International Trail Running Association) "Kilometer-Effort" unit: distance + D+/100. We add a descent-cost term (+ D-/150) on top of that to reflect the real eccentric muscle load of steep descents — ITRA's own formula uses D-/500, which treats descent as almost free. Because of this, the km-effort shown here won't always match ITRA's own official calculator exactly — that's a deliberate difference, not a bug.
Elevation Smoothing
Raw GPX elevation data is noisy — summing every consecutive point-to-point delta directly wildly overstates total climb/descent. We run the elevation profile through a moving average before any of the math below, which removes most of that sensor noise while barely touching real climbs and descents.
Steepest Grade
Measured over ~100m rolling windows along the route rather than a single point-to-point spike — this reflects a real sustained pitch instead of one noisy GPS reading.
Sources: ITRA's Kilometer-Effort methodology · Minetti et al. (2002), "Energy cost of walking and running at extreme uphill and downhill slopes", Journal of Physiology.
Frequently Asked Questions
How accurate is GPS elevation data?
It varies by device — barometric-altimeter watches (most trail running watches) are generally more accurate than phones. Raw GPX data is always a bit noisy, which is why we smooth it before calculating anything (see above).
Why does my km-effort differ from the official ITRA value?
We add a descent-cost term (+ D-/150) on top of ITRA's base formula (distance + D+/100); ITRA itself uses D-/500. Both are real, published approaches — they just make different assumptions about how much descent contributes to difficulty.
What's the difference between D+ from GPS and D+ from a topo map?
GPS/barometric data is real-time and noisy; topo maps typically use smoother, officially-surveyed elevation models. A few percent difference between the two is normal.
Can I use a planned route GPX (not a recorded activity)?
Yes — every stat here (distance, climb/descent, km-effort) is derived purely from the route's coordinates and elevation data, not from any recorded timing information.
What does the steepest grade figure mean?
It's the steepest elevation change measured over ~100m sections along the route — a real sustained pitch, not a single noisy GPS spike.