GPX course analysis
Pick the GPX file of a course and we work out the distance, the climbing, the elevation profile and a kilometre-by-kilometre finish estimate from your flat pace.
Pick the GPX file of the course
For example 5:30
The file never leaves your browser: everything is calculated on your device.
Distance is the sum of great-circle (haversine) distances between consecutive points. Ascent and descent use a 3 metre threshold so GPS elevation noise does not inflate them, which means our number can be lower than the one your device shows. The time estimate takes the gradient of every segment and adjusts your flat pace accordingly: the Minetti cost curve uphill, a braking-corrected curve downhill. It excludes aid stations, technical ground and fatigue. The file is not uploaded anywhere; everything runs in your browser.
These are general ranges and assume normal conditions. Trail, heat, elevation gain, wind and technical ground all make the real time longer.
Frequently asked questions
(10)
What is a GPX file and where do I get one?
GPX is the standard format for the coordinates and elevation points of a route. Organisers usually publish one on the course section of the race site, and Strava, Garmin Connect, Komoot and Wikiloc all let you export your own routes as GPX.
Is my file uploaded to a server?
No. The file is read in your browser and the maths runs there; no point of it is sent to us or stored. Close the page and the data is gone.
Why is your ascent figure different from my watch?
Two reasons: watches with a barometric altimeter read differently from GPS-based files, and we apply a 3 metre threshold to filter noise. Adding every wobble invents hundreds of metres of climbing even on a flat course, so our figure is usually the more conservative one.
How reliable is the finish estimate?
It models the gradient well, and only the gradient. Aid station stops, technical ground, mud, running at night, heat and fatigue are not included. On long ultras the real time runs clearly above the estimate; on short runnable courses it lands close.
What happens if the course belongs to a race in your calendar?
If the start point and the distance line up with a race we list, we show that race and the matching course under the result, with a link to its date, entry deadline and registration page.
What do km-effort and the ITRA category mean?
Km-effort is a difficulty unit made of distance plus one hundredth of the ascent (45 km + 2,500 m = 70 km-effort). ITRA uses it to sort races into seven sizes from XXS to XXL. The analysis calculates both from your file.
How do I export a GPX from Strava?
Open the route on Strava and choose Export GPX from the three dot menu; for an activity the same menu offers Export Original or Export GPX. On Garmin Connect it is Export to GPX under the gear icon, and on Komoot it is Download GPX on the route page.
How many points should a GPX have, and what if mine is huge?
20-100 points per kilometre is plenty, so 2,000-4,000 points suits a 40 kilometre course. Files over 12 MB are rejected and anything past 20,000 points is thinned, because extra points add noise rather than accuracy.
What happens if my file has no elevation data?
Distance, the kilometre plan and the time estimate still work, but ascent shows as zero and no gradient correction is applied, so you get a flat-ground result. Files without elevation are usually routes drawn on a map rather than recorded activities.
Why does race day distance differ from the course GPX?
Three reasons: the organiser file is usually the planned line while you run wide through corners, GPS drifts under trees and in canyons, and a low point density cuts corners. A 2-4% difference is normal on trail courses.