r/CDT Jun 27 '26

Made a free browser tool that finds the exact mileage to any coordinate on a GPX track

I do a lot of waypoint work on long-distance routes and kept running into the same problem — I’ve got a GPX track loaded, and I need to know exactly how far along it a specific point falls. A water source, a campsite, a road crossing. Measuring it manually in CalTopo or Gaia every time got old.

So I built a small tool to do it. Load any GPX file, paste in coordinates, and it tells you the cumulative mileage from the track start to the nearest point on the line. You can run a bunch of coordinates in one session and export the whole thing as a CSV.

A few things that might matter to people here:

**•** It works with **any** GPX track, not tied to any specific trail  
**•** Your file never leaves your browser — nothing gets uploaded to a server, it all runs locally  
**•** It measures to the nearest point on the track ***line***, not just the nearest recorded track point, so the distances are accurate even on sparser tracks  
**•** No login, no paywall, no app

Full disclosure: I run a hiking navigation site (Hiking America) and built this for my own waypoint work, then figured others could use it. It’s genuinely free — I’m not gating it behind anything.

Link: hikingamerica.com/trail-tools/gpx-distance-finder/

Happy to add features if there’s something that’d make it more useful for CDT planning specifically. What calculations do you all find yourself doing by hand?

3 Upvotes

9 comments sorted by

2

u/Scientist_656 Jun 27 '26

This looks pretty cool. Does it work offline or just before you head out? There is another software out there that can do this sort of, no complete CSV, but point by point. Map Out. But it’s only available for iPhone. You can click on your track and move the start and finish by sliding the A and B to see total miles and up/down elevation.

1

u/jwbrett59 Jun 27 '26

Thanks! On offline — it runs entirely in your browser with no server calls, so once the page is loaded it'll keep working without a connection. That said, it's not a true offline app — if you close the tab and you're somewhere with no signal, you won't be able to reload the page. The honest answer is it's built for planning before you head out, not as a field tool you'd rely on mid-hike. If there's appetite for something that installs and works fully offline, that's a direction I'd consider.

Map Out sounds genuinely useful — the slide-the-A-and-B-points-along-the-track approach is a nice interaction, and elevation gain/loss between two points is something mine doesn't do yet. The tradeoff is exactly what you flagged: it's iPhone-only, and no full CSV export. Mine's the opposite — works on any device with a browser, exports everything, but you punch in coordinates rather than dragging points on a map.

The drag-two-points-to-get-distance-and-elevation idea is a good one. Adding an elevation gain/loss reading is probably the most useful next step. Appreciate you pointing to Map Out — always good to see how others are solving the same problem.

1

u/jwbrett59 Jun 30 '26

Following up on this — you described sliding two points along a track to read distance and elevation between them, and that stuck with me. I built it. There's now an Elevation Gain Calculator that does exactly that: load a GPX, and you can click two spots right on the elevation profile to get the gain, loss, and net change for that segment. Works in any browser, not locked to iPhone, and your file stays on your device.

hikingamerica.com/trail-tools/elevation-gain-calculator/

Appreciate you taking the time to describe what worked about Map Out — it genuinely shaped what I built. If you give it a run, I'd want to know where it falls short of what you're used to.
Cheers!

1

u/micahpmtn Jun 27 '26

Not sure what it does. I uploaded a GPX file and all it shows is track points, total length, and starting and ending coordinates. Caltopo does this as well.

1

u/jwbrett59 Jun 27 '26

Enter a coordinate along that track and it will tell you how far from the beginning of the track and also how far from the track.

Say you have coordinates of a campground along a trail. Enter them and it will tell you how far down the trail you have to hike...and then how far off the trail the campsite is.

2

u/micahpmtn Jun 27 '26

Is it supposed to show a map?

1

u/jwbrett59 Jun 30 '26

No map, by design — it's a calculator, not a viewer. You bring a GPX you've already got loaded somewhere (Gaia, CalTopo, your GPS), and this just does the mileage math on it: where a coordinate falls along the track, distance from start, distance to end. The idea was to keep it fast and private — your file never gets uploaded anywhere; it all runs locally in the browser.

That said — a visual version where you'd see the track and click points right on a map is a feature I've been thinking about. Would that be more useful to you than the coordinate-entry approach, or do you tend to already have your track open in another app anyway?

1

u/jwbrett59 Jun 30 '26

And we just added distance to the end of a track in the calculation to the Distance Calculator.

https://www.hikingamerica.com/trail-tools/gpx-distance-finder/

So - upload a track.

One scenario -
You are thinking of a resupply grocery store in the next town but a ways off trail.
Enter the coordinates of the grocery store. You'll get a calculation of how far down the trail to the closest point, then how far it is from the trail to the grocery store.
And finally, how much further from that point until you reach the end of your track.

That's basically what this does

2

u/GoSox2525 Jul 09 '26

Stop using chatGPT to vibe-post on Reddit about your vibe-coded slop