Geo Calculator plots and measures geocaching coordinates on a map — converting between formats, projecting by bearing and distance, and finding intersections, midpoints, overlaps and triangle centers between points. This page explains every input and option in depth.
Quick start
- Type a coordinate into the Coordinate box (any supported format — it is auto-detected).
- Optionally add a Bearing and/or Distance to project a new point from it.
- Tick the map options you want (distances, intersections, centers…) and press Calculate & Update Map.
- Add more points from the Select Coordinates dropdown to compare and combine them.
Everything is computed in your browser — nothing is uploaded.
On this page
Coordinate input formats
The Coordinate box accepts several formats. They are auto-detected in
this order: RD → degrees-minutes-seconds → degrees-decimal-minutes → UTM → decimal.
Direction can be given by an N/S/E/W letter or by a sign.
| Format | Example | Notes |
|---|---|---|
| GPS (deg + decimal minutes) | N38 25.3346 W78 44.5698 | The common geocaching format. ° and ' marks optional;
, ; & or spaces separate lat/lon. |
| Degrees-minutes-seconds | N38 25 20.1 W78 44 34.2 | Three numbers per axis. |
| Decimal degrees | 38.4222433, -78.7428300 | Comma- or space-separated. Negative = South / West. |
| UTM | 17N 747445 4257945 | Zone + hemisphere, easting, northing. |
| RD (Dutch Rijksdriehoek) | RD 155000 463000 | Prefix with RD. |
Two parsing conveniences: any text before a final = in the line is
ignored (so you can prefix a label), and a trailing ,#… is stripped.
Display / output format
The selector next to Coordinate: (GPS, Decimal, Minutes, UTM, RD) controls how coordinates are shown — it reformats the read-only "adjusted" preview beside the box and every coordinate printed in the output panel. Input format and display format are independent, so this is also a quick way to convert a coordinate: paste it in, pick a different display system, and read the result.
Points & saving your work
The tool holds up to 98 points, chosen from the Select Coordinates dropdown. Each point stores its own Coordinate, Alias (a label), Bearing and Distance. Switching points saves the current one and loads the next.
- Multi-line paste: paste several coordinates (one per line) into the Coordinate box and they fill consecutive points automatically.
- Update: opens a box containing all your points as JSON text. Copy it to save your work, or paste a previously saved set back in to restore it.
- Clear: empties all points and resets the scale to 1.
Bearing & distance
Bearing is a compass direction in degrees (0–360, clockwise from North).
Enter it as a decimal (137.5) or as degrees-minutes-seconds
(137 30 0).
Distance is a number with an optional unit. The Units dropdown sets the default unit and the unit used in the output, but you can also type a unit word right after the number to override it. Recognised units:
- km / kilometers, miles, yards, feet, meters, nautical miles (nm / minutes),
inches, cm, furlong, chain, rod — and the novelty unit fizzies
(
1/πkm).
Scale multiplies every distance by a factor — handy when a puzzle gives distances in an unknown unit or at a fixed ratio.
Projections
Give a point both a bearing and a distance and the tool projects a new point that far away in that direction, drawing it (and printing its coordinate) when you calculate. Give a point a bearing only (no distance) and it draws an open ray in that direction — useful for finding where two directions cross (see Intersections).
Reference syntax (linking points)
Instead of fixed values, a point's fields can reference another point by its
number, so a chain of stages updates automatically. Start the field with =:
| Field | Syntax | Meaning |
|---|---|---|
| Coordinate | =3 | Use point 3's coordinate. |
| Coordinate | ==3 | Use point 3's projected point (its bearing/distance endpoint). |
| Bearing | =3 | Same bearing as point 3. |
| Bearing | =>3 | Point 3's bearing + 90°. |
| Bearing | =<3 | Point 3's bearing + 270° (i.e. − 90°). |
| Bearing | =-3 | Point 3's bearing + 180° (reverse). |
| Distance | =3 | Same distance as point 3. |
Calculation models
The model dropdown (next to Show Bearings) sets the geometry used for all distances, bearings, projections and intersections:
- Vincenty — highly accurate ellipsoidal (WGS-84) model. The default; best for real-world distances.
- Great Circle — spherical-earth model; slightly simpler.
- Flat Earth — treats the local area as a flat plane; fast and a good match for some puzzles that were designed that way.
Map options
Each checkbox adds a calculation to the output (and markers/lines on the map):
| Option | What it shows |
|---|---|
| Show Gridlines | A latitude/longitude grid overlay (hidden automatically when zoomed far out). |
| Show Bearings | The bearing from each point to every other point. |
| Show Distances | The distance between each pair of points, in the selected unit. |
| Show Intersections | Where two points' bearing lines cross. |
| Show Circle Intersections | Where distance circles cross — circle×circle (two distances) and bearing×circle. |
| Show Overlaps | The overlap area of two points' distance circles. |
| Show Midpoints | The midpoint of each pair of points. |
| Show Angles | The three interior angles of the triangle formed by the first 3 points. |
| Show Centers | For the first 3 points: Circumcenter, Incenter, Centroid and Orthocenter; and for 2 points + a bearing, the cross-fix circle center. |
Angles and Centers use only the first three points.
Buttons
- Calculate & Update Map — runs every selected calculation, prints results to the output panel and redraws the map to fit all points.
- Zoom — recenters and zooms the map tightly on the current point.
- Connect Dots — fills in each point's bearing and distance as a running chain (point 1→2, 2→3, 3→4…), measuring the path between consecutive points.
- Pair Dots — like Connect Dots but measures independent pairs (1→2, 3→4, …), resetting after each pair.
Tips & deep links
- Pre-load a coordinate by URL: open index.html?StartCoord=N52 12.345 E5 06.789 and the tool fills point 1 and zooms to it.
- Solve multi-stage puzzles by combining projections with
references: later stages can reference an
earlier stage's projected endpoint with
==N, so editing stage 1 re-flows the whole solution. - Convert formats fast by pasting a coordinate and switching the display selector.