Converts to WGS84 lat/lon with links to a few mapping services.

First define the datum of the original coordinates to be converted (see reference 1, appendices A, B, and C). If you stumble on this page while searching, and would like to see another datum and/or ellipsoid added to this page, don't hesitate to write to me (ref at bottom).

Fill **one** of the following three boxes; the first one with non-empty data provides the original
coordinates in above datum.

Click on button below to transform the coordinates into WGS84:

Output area, results of transformation will appear here.

- MGRS has two conventions for the two-letter code identifying a 100-km square, see reference 2 below. If you get insane results (~1000 km off in latitude) with the usual (first) convention on an old datum, you can try the alternate (second) convention.
- For squares greater than 1m (ie. with less than 10 digits), you can specify whether the transformed coordinates will point to the SW corner (usual) or the center of the square (possible enhancement: draw the square).
- Most UTM zones are 6° wide and 8° high. There are a few exceptions in Northern Europe that this web page (and all others I've seen) does not take into account. See map of UTM zones by Alan Morton.

- https://gis-lab.info/docs/nima-tr8350.2-wgs84fin.pdf (basics, Molodensky transform — I will align my terminology with them)
- https://www.maptools.com/tutorials/100km_square_id (MGRS 100,000-meter Square Identification)
- Official NAD27 to NAD83 conversion for Canada
- https://maps.lib.utexas.edu/maps/topo/vietnam/ (collection of old military maps of Vietnam that I used for initial development)
- Another site for these conversions (much more comprehensive) can be found here (altho it does not seem to support UTM or MGRS in all cases).
- And finally, the PyGeodesy python package is another option for someone comfortable working at the command-line level. I don't know much about this package, but a small word of caution: it seems that the signs of ΔX, ΔY and ΔZ (
`tx`

,`ty`

and`tz`

in the package) are flipped in datums (something to consider if you get insane results).

- Intersection in Huế: original MGRS 48Q YD 74869 21364 (map 6541-4 from reference 4 below)
- Intersection south of Quảng Trị: original UTM 48Q 734031 1851751 (map 6442-3 from reference 4 below)
- Intersection in Gò Công: original UTM 48P 684261 1145344 (map 6329-4 from reference 4 below)
- A park (?) in Haiphong: original UTM 48Q 676346 2306122 (aka 48Q XJ 763061) (map 6350-4 from reference 4 below)
- Intersection in Bagotville, NAD27 UTM 19U 360487 5355430 (test for NAD27)
- Reference point in Winnipeg, NAD27 UTM 14U 633861 5518644 (test for NAD27, should give 49.807313, -97.140025 — there are unexplained discrepencies of about 5 meters between the conversion done by the tool of reference 3 compared with my results which also match those of my Garmin GPS72)
- Rawson, Argentina: WGS84 UTM 20G 329665 5203729 (this and next add testing to cover all four quadrants, north vs south, east vs west)
- Perth, Australia: WGS84 UTM 50J 392157 6464292

Back to home page. If you have suggestions, and especially if you have problems, don't hesitate to contact me: (français, English, Deutsch).

Version 3, 2022-02-03. Previous version 2 was Vietnam only.

This page was done to learn about this aspect of geomatics.