Coordinate converter — DD, DMS, DDM, UTM, MGRS

The part that works

One position, written every way it can be written.

Type a coordinate in any notation — decimal degrees, degrees-minutes-seconds, degrees-decimal-minutes, UTM or MGRS. It is parsed and re-emitted in all of them, live, in your browser. Nothing is sent anywhere; there is no server to send it to.

Coordinate converterlive_local

Coordinate — any notation

The UTM grid, to scale: 60 zones of 6° longitude across, 20 latitude bands of 8° up (band X is 12°). The lit cell is the one your coordinate falls in; the inset is its MGRS 100 km square. That is the whole of what the zone and band letters mean.

Also arithmetic

How far apart, and which way.

Distance and bearing on the WGS84 ellipsoid by Vincenty's inverse method. The sphere-based answer sits next to it, because the gap between the two is the honest measure of how much the Earth's shape matters for your particular pair.

Distance & bearinglive_local

From

What it will not convert, and why

Two formats are missing on purpose.

The previous version of this site counted six formats "in scope" and implied all six were coming. Five are real and above. Here is the honest account of the other two.

Plus Code

spec

Open Location Code is pure arithmetic and openly specified, so it could join the converter with no data and no cost. It simply is not written yet, and the converter will not show a format it has not checked against a reference value.

Needs: An implementation and a reference-value check. Built: no.

what3words

spec

Permanently unavailable here, not merely unbuilt. The wordlist and the assignment are proprietary and a correct conversion requires a licensed API call, so it cannot be a client-side function and will never appear in this converter.

Needs: A commercial licence and a server. Built: no, and not planned.

The receipt

Checked against three implementations we did not write.

UTM vs PROJ 9.5.1

max 7 × 10⁻⁹ m

Worst disagreement in forward easting or northing of any single one of the 4,000 points, in metres. The inverse transform agrees to the same order.

MGRS vs NGA GEOTRANS

0 mismatches / 4,000

Every 5-digit MGRS string produced here is character-for-character identical to the one GEOTRANS produces for the same point.

Distance vs GeographicLib

max 7.5 × 10⁻⁵ m

Over 1,500 random pairs. Initial and final bearings agree to within 1 × 10⁻⁵ arcseconds.

Reproduce it

node check.mjs

No dependencies and no network. It reads src/coord.mjs and asserts it against the frozen records below, so the arithmetic and the published tables cannot drift apart.

Reference point	Latitude	Longitude	UTM	MGRS
Null Island — the equator on zone 31’s central meridian	0.0000	3.0000	31N 500000.00 0.00	31NEA0000000000
Greenwich Royal Observatory	51.4779	-0.0015	30U 708213.49 5707235.66	30UYC0821307235
Seguin, Texas	29.5688	-97.9644	14R 600313.02 3271453.85	14RPT0031371453
Sydney Opera House	-33.8568	151.2153	56H 334900.57 6252288.75	56HLH3490052288
Bergen, Norway — where zone 32 is widened	60.3900	5.3200	32V 297230.22 6700510.18	32VKN9723000510
Longyearbyen, Svalbard — where zone 32 does not exist	78.2200	15.6300	33X 514357.74 8682999.17	33XWG1435782999
Ushuaia, Argentina	-54.8019	-68.3030	19F 544805.10 3927029.88	19FEV4480527029
Kathmandu, Nepal	27.7172	85.3240	45R 334769.78 3067000.01	45RUL3476967000

These eight rows were recomputed by the build from the same code this page runs, and the build refuses to publish if any of them disagrees with the frozen record. The distance pairs below are held to the same rule.

Pair	Geodesic distance	Initial bearing	Final bearing
Greenwich → Sydney Opera House	16982.637 km	60.5603°	139.1706°
Seguin → Kathmandu	13654.938 km	356.5571°	183.3829°
Bergen → Longyearbyen	2022.646 km	6.7502°	16.5156°

Status: live_local — The converter and the distance tool run end to end in a browser on a developer machine. Nothing else on this domain is implemented.
Last verified: 2026-08-17
Source: check.mjs in this repository, against eight reference points that PROJ 9.5.1 and NGA GEOTRANS independently confirmed.
Limit: This establishes that the arithmetic is correct. It does not establish that anyone has used it, that it behaves the same in a browser other than the one it was tested in, or that a single other thing described on this site exists. It has not been exercised on the deployed domain, so the rung is live_local and not live_deployed.
Next rung: live_deployed — Deploy, then load https://gpscoord.com/convert/ and convert one coordinate there. The domain currently answers every path with the same homepage, so until that check runs it is unknown whether the route resolves at all.

What you can do here

It is running. Try to break it.

live_local — run and checked

Use itIt is above. Paste anything — the parser tells you what notation it decided you meant.Reproduce it locallynode check.mjs re-proves every published value with no dependencies and no network.