Initially, QRZ will calculate a grid square based on your documented address. QRZ.com includes the grid square for each ham in their database.

Typically hams put their grid square location on their business cards, email signatures, and QSL cards. With the onset of computer integration into the hobby, these are used to plot map positions of stations, repeaters, vehicles, shelters, and more. Initially, these codes were used to classify each station’s location so contesters could have something to conquer during HF/VHF/UHF contests. So, the 4 characters can break the globe into 324,000 squares, and the 6 characters can break the globe into 18,662,400 sub-squares that all hams can use to find a location very quickly.

Additional characters can be added for more precision, but none have been formally approved.

This provides 576 subsquares per square that are 5 minutes wide and 2.5 minutes tall.

The fifth and sixth characters use the lower case letters ‘a’ through ‘x’ to split each square into 24 vertical and 24 horizontal subsquares.And we are in the 6th block east of the west border, ‘5’. We are in the second block from the bottom of the zone, ‘1’. These grid squares are 2 degrees wide by 1 degree high and start their numbering in the bottom left of each zone as 00 and end in each zone’s top right as 99. The third digit is the horizontal dimension, and the fourth digit is the vertical digital. Characters three and four use the numbers zero through nine to break each of the 324 zones into 100 grid squares.We’re in the 13th zone north from the South Pole, ‘M.’ We’re in the fifth zone east of that line, ‘E.’ The vertical, or second character, starts at the south pole and ends at the north pole. This is positioned in the western Pacific Ocean, just west of Alaska. The horizontal letter starts at the antimeridian of Greenwich with the letter A. The two-digit code breaks the globe into 324 different zones that are 20 degrees wide by 10 degrees high.

The first two characters are always in the range of uppercase ‘A’ through ‘R.’ This provides 18 divisions of latitude and longitude.

The four-digit code is used for HF contact positioning where the higher accuracy is needed. The six-digit format is typically used for VHF/UHF and higher contacts. A rougher representation of the post office is EM15. For example, the six-digit code for the Norman Main Post Office is EM15ef. The Maidenhead Locator System was developed and adopted in 1980 by John Morris G4ANB to quickly and concisely document a person’s location. Have you ever been asked for your grid square or your coordinates, and you had no idea what these were? I know the first time I had to figure out my location in this strange shorthand notation, it took a lot of effort.

Ham radio grid map