How to use the maidenhead locator converter
- Choose coordinates to locator or locator to coordinates.
- For coordinates, enter the latitude and longitude in decimal degrees (north and east positive) and pick a locator length of 4, 6 or 8 characters.
- For a locator, type it with 4, 6 or 8 characters, such as JN58 or JN58td.
- Optionally enter a second locator to see the distance and starting direction between the two squares.
Formula
field: (longitude + 180) / 20 and (latitude + 90) / 10, letters A to R
square: remaining / 2 and / 1, digits 0 to 9
subsquare: remaining / (2/24) and / (1/24), letters a to x
extended square: remaining / (2/240) and / (1/240), digits 0 to 9
Each pair of characters divides the previous cell into a finer grid. A 4-character locator is a cell of 2 by 1 degrees, 6 characters 5 by 2.5 minutes and 8 characters 30 by 15 seconds. Distance uses the haversine formula with a mean Earth radius of 6,371 km.
A point in Munich
Latitude 48.14666 and longitude 11.60833 give the 4-character locator JN58, the 6-character locator JN58td and the 8-character locator JN58td25. The square JN58td has its center at 48.14583, 11.62500, its south-west corner at 48.12500, 11.58333 and its north-east corner at 48.16667, 11.66667.
Converting back from a locator returns the center of the square, not the original point. The distance from the center of JN58td to the center of FN31pr in Connecticut is 6,335.8 km (3,936.9 miles) on an initial heading of 297.7 degrees from north.
What a Maidenhead locator is
The Maidenhead system gives every place on Earth a short code that names a rectangle of the globe. Amateur radio operators use it to exchange their location in a few characters, and contests count the squares worked. Longer codes mean a smaller square, so a 4-character locator covers about 111 km north to south and a 6-character locator about 4.6 km.
Upper-case letters are used for the field and lower-case for the subsquare by custom. The page accepts either case and writes the standard form.
Edges and accuracy
Points on a boundary belong to the cell to the north and east. Latitude 90 and longitude 180 sit at the very edge of the grid, and the page places them in the last cell before the edge. For the time at a place, see the Time Zone Converter or the Sunrise Sunset Calculator, and for areas given by corner coordinates the Polygon Area Calculator.
More hobby and sport tools
For other hobbies, sports and music, try the Poker Chip Distribution Calculator, Cycling Climb Speed Calculator and Darts Checkout Calculator.
Assumptions and limits
- Coordinates are decimal degrees in the WGS 84 style used by most maps and GPS devices.
- A locator names a square, and conversion back gives the center of that square.
- Distances are great circle distances between square centers on a sphere, not road distances.
- The locator must follow the pattern of two letters A to R, two digits, optionally two letters A to X and two digits.
Frequently asked questions
How big is a 6-character square?
It is 5 minutes of longitude by 2.5 minutes of latitude. That is about 9 km wide at the equator and 4.6 km tall, narrowing toward the poles.
Why does converting back not give my original coordinates?
A locator stands for a whole square, so the page gives the center. A longer locator keeps the center closer to the original point.
What do the first two letters mean?
They name the field, a block 20 degrees of longitude wide and 10 degrees of latitude tall. A is the field at the far west and south, and R at the far east and north.
Can I enter coordinates in degrees, minutes and seconds?
Not directly. Convert them to decimal degrees first: degrees plus minutes divided by 60 plus seconds divided by 3,600, with a minus sign for south or west.