GPS Coordinate Converter (Lat/Long, DMS, UTM, MGRS)

About the GPS Coordinate Converter (Lat/Long, DMS, UTM, MGRS)

Paste a position in almost any form and get all the others at once: decimal degrees, degrees, minutes and seconds (DMS), degrees and decimal minutes (DDM), UTM with its zone and latitude band, MGRS and the US National Grid, Plus Codes and geohash — and, under More formats, Maidenhead locators, ISO 6709, geo: URIs, GeoJSON, WKT, KML and ECEF. The converter recognises the notation by itself — 40°41'21.29"N 74°02'40.21"W, N 40° 41.355 W 074° 02.670, 18T 580736 4504700, 18TWL8073504700, 87G7MXQ4+M5, a map link or an NMEA sentence from a GPS receiver — and says how it read it.

Everything is worked out in your browser on WGS 84, the datum GPS uses; nothing you type is sent anywhere. UTM uses Karney’s sixth-order Krüger series and UPS the polar stereographic projection, as GeographicLib does, and the tests check both against GeographicLib’s own converter; Plus Codes pass every test case the Open Location Code project publishes. Each result says how precise it is, and a code that stands for an area — an MGRS square, a Plus Code or geohash cell — is converted from the centre of that area, with its size shown.

Common uses

• Turning a GPS unit’s, phone’s or photo’s coordinates into the format a form, map, app or colleague needs.
• Search and rescue, emergency and military work in MGRS or the US National Grid, with the size of each square spelled out.
• Surveying and GIS: UTM with the EPSG code, the meridian convergence and the point scale factor.
• Geocaching, hiking and sailing in degrees and decimal minutes.
• Developers checking geohashes, WKT, GeoJSON and ECEF values, or reading NMEA sentences from a receiver.
• Amateur radio grid squares (Maidenhead locators) for logs and contests.
• Finding a Plus Code someone sent you in any map app.

The formats side by side

• Decimal degrees (DD): latitude, then longitude, negative for south and west: 40.689247, -74.044502.
• Degrees, minutes, seconds (DMS): 60 minutes to a degree, 60 seconds to a minute: 40°41'21.29"N 74°02'40.21"W. One second of latitude is about 31 m.
• Degrees and decimal minutes (DDM): 40°41.3548'N — the format of most handheld GPS units, nautical charts and geocaching (N 40° 41.355). A minute of latitude is about 1,852 m, one nautical mile.
• UTM: a zone (1–60, each 6° of longitude), a latitude band letter (C–X, each 8°) and an easting and northing in metres: 18T 580736 4504700. Eastings start 500,000 m west of the zone’s central meridian; northings start at the equator in the north and 10,000,000 m south of it in the south.
• MGRS and USNG: UTM written as the grid zone (18T), two letters for the 100 km square (WL) and 1–5 digits each of easting and northing within it: 18T WL 80735 04700 is a 1 m square, 18T WL 807 047 a 100 m square.
• UPS: the polar stereographic grid used instead of UTM north of 84° N and south of 80° S; MGRS calls its halves A and B (south) and Y and Z (north).
• Plus Codes (Open Location Code): 87G7MXQ4+M5; 10 characters name a cell of about 14 m × 14 m at the equator. Short codes such as MXQ4+M5 New York leave out the first four characters and need a nearby town.
• Geohash: base-32 characters that halve the cell with every bit; 9 characters are about 5 m × 5 m at the equator, and every prefix is a larger cell around the same point.
• Maidenhead locator: amateur radio’s grid squares, FN20xq: field (20° × 10°), square (2° × 1°), subsquare (5′ × 2.5′) and an optional extended square.
• ECEF: Earth-centred, Earth-fixed X, Y and Z in metres, as GNSS receivers use internally. It needs a height above the ellipsoid, which is not the height above sea level.

UTM zones, latitude bands and the exceptions

Zones are numbered eastwards from 180° W: zone 1 covers 180°–174° W, zone 18 covers 78°–72° W and zone 43 covers 72°–78° E. Bands run from C (80°–72° S) to X (72°–84° N) without I and O; N is the first band north of the equator, so the band letter also gives the hemisphere. Two areas break the pattern: off south-western Norway zone 32V is widened to cover 3°–12° E, and around Svalbard zones 31X, 33X, 35X and 37X are widened while 32X, 34X and 36X are not used. The converter applies both.

A letter after the zone can be a band (as MGRS writes it) or a hemisphere (as some GIS software writes it), so 33S is ambiguous: band S is 32°–40° N, but S can also mean south. The converter reads it as band S when the northing fits that band, says so, and offers the southern hemisphere instead; a lower-case 33s, the way GeographicLib writes the southern hemisphere, is read as south. For a project that crosses a zone boundary, Precision and options can put UTM in a neighbouring zone: the coordinates stay valid, they are just outside the zone’s usual strip.

Reading an MGRS reference

18T WL 80735 04700 has four parts: the grid zone 18T, the 100 km square WL, then the same number of easting and northing digits. Fewer digits mean a bigger square: 5 each for 1 m, 4 for 10 m, 3 for 100 m, 2 for 1 km and 1 for 10 km. MGRS truncates instead of rounding, so a reference names the square the point lies in; the converter returns the centre of that square, as GeographicLib does, and shows its size. The square letters repeat every 2,000 km from south to north, so the band letter is what places them: the converter checks that the square really lies in the band and explains the mistake when it does not. A grid zone on its own, such as 18T, stands for the whole 6° × 8° zone: the converter shows its extent and uses the same point inside it as GeographicLib.

How precise is each result?

• Decimal degrees: 4 decimals ≈ 11 m, 5 ≈ 1.1 m, 6 ≈ 0.11 m of latitude (east–west steps shrink towards the poles).
• DMS: 1″ ≈ 31 m, 0.1″ ≈ 3 m, 0.01″ ≈ 0.3 m. DDM: 0.001′ ≈ 1.9 m, 0.0001′ ≈ 0.19 m.
• UTM and UPS: whole metres by default, up to millimetres.
• MGRS: squares of 1 m to 10 km. Plus Codes: 10 characters ≈ 14 m, 11 ≈ 3 m. Geohash: 7 characters ≈ 150 m, 9 ≈ 5 m, 12 a few centimetres.

Precision is not accuracy: a phone or GPS unit is often off by several metres, more between tall buildings or under trees. Use my location shows the accuracy your device reports with its position, so you can choose a sensible precision.

Datums: why the same numbers can be metres apart

All conversions here use WGS 84, the datum of GPS and of web maps. Coordinates from older maps and national survey systems may be on another datum — NAD27, ED50 or Everest 1830, for example — where the same latitude and longitude can lie tens or hundreds of metres from the WGS 84 point. The converter does not transform between datums, and national grids such as the British National Grid are different projections, not UTM. Modern regional datums such as NAD83 and ETRS89 differ from WGS 84 by roughly a metre or two, which matters mainly for survey work.

Map services in mainland China show positions on GCJ-02 (Baidu on its own BD-09), systems that shift coordinates on purpose, often by several hundred metres. Coordinates copied from them are not GPS positions; the converter reads them as WGS 84 and says so when the link is from one of those services.

Method and sources

• Ellipsoid: WGS 84, a = 6,378,137 m and 1/f = 298.257223563 (NGA.STND.0036).
• UTM and UPS: zones, scale factors (0.9996 and 0.994) and false origins from NGA.SIG.0012; MGRS lettering from NGA.STND.0037 (all listed on NGA’s coordinate systems page). EPSG codes as registered for WGS 84 UTM and UPS (EPSG:32618, for example).
• Transverse Mercator: Krüger’s series to sixth order as given by C. F. F. Karney, Transverse Mercator with an accuracy of a few nanometers, Journal of Geodesy 85; GeographicLib documents a maximum error of 5 nm for this series within 35° of the central meridian. The tests compare UTM and UPS with GeographicLib’s GeoConvert at 19 reference points to within 0.2 mm, and convert thousands of random positions there and back.
• Plus Codes: the Open Location Code specification; all 766 encoding, decoding, short-code and validity test cases the project publishes pass.
• Others: geohash is Gustavo Niemeyer’s public-domain system; the Maidenhead locator is described by the ARRL; geo: URIs follow RFC 5870, GeoJSON RFC 7946, and the FGDC’s US National Grid standard uses the same numbering as MGRS across the United States.

Limitations

• WGS 84 only: no datum transformations (NAD27, ED50, OSGB36, China’s GCJ-02 and others) and no national grids such as the British National Grid.
• One position at a time: from several lines the first position is converted, and several positions on one line are refused.
• Heights are not converted. A GPS altitude above sea level is not the height above the ellipsoid that ECEF needs; ECEF uses the height you set.
• Short Plus Codes need a nearby place. The built-in list has about 2,000 large cities; for a village, type a nearby town from the list or coordinates. Addresses and place names are never looked up online.
• Shortened map links (such as maps.app.goo.gl) contain no coordinates, and this page does not open links; what3words addresses cannot be converted.
• MGRS is always given in the standard zone, even when UTM is shown in a neighbouring zone.
• This is a converter, not a navigation or survey instrument: check positions that matter for safety against a second source.

Privacy

Everything is converted in your browser; nothing you type or paste is sent to MySmartCoPilot or anyone else. Use my location asks your browser for permission, and the position stays on this page. Your precision settings are remembered in this browser; Reset forgets them. The map links are ordinary links: nothing is sent to a map service unless you open one.