Maidenhead Grid Squares

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. The Maidenhead Locator System was developed and adopted in 1980 by John Morris G4ANB to quickly and concisely document a person’s location. For example, the six-digit code for the Norman Main Post Office is EM15ef. A rougher representation of the post office is EM15. The six-digit format is typically used for VHF/UHF and higher contacts. The four-digit code is used for HF contact positioning where the higher accuracy is needed.

  • The first two characters are always in the range of uppercase ‘A’ through ‘R.’ This provides 18 divisions of latitude and longitude. The two-digit code breaks the globe into 324 different zones that are 20 degrees wide by 10 degrees high. The horizontal letter starts at the antimeridian of Greenwich with the letter A. This is positioned in the western Pacific Ocean, just west of Alaska. 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. We’re in the 13th zone north from the South Pole, ‘M.’
  • Characters three and four use the numbers zero through nine to break each of the 324 zones into 100 grid squares. The third digit is the horizontal dimension, and the fourth digit is the vertical digital. 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. We are in the second block from the bottom of the zone, ‘1’. And we are in the 6th block east of the west border, ‘5’.
  • The fifth and sixth characters use the lower case letters ‘a’ through ‘x’ to split each square into 24 vertical and 24 horizontal subsquares. This provides 576 subsquares per square that are 5 minutes wide and 2.5 minutes tall.
  • Additional characters can be added for more precision, but none have been formally approved.

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.

Grid Square Uses

Initially, these codes were used to classify each station’s location so contesters could have something to conquer during HF/VHF/UHF contests. With the onset of computer integration into the hobby, these are used to plot map positions of stations, repeaters, vehicles, shelters, and more. Typically hams put their grid square location on their business cards, email signatures, and QSL cards.

QRZ.com includes the grid square for each ham in their database. Initially, QRZ will calculate a grid square based on your documented address. However, you can log into your QRZ account and adjust your location to sequence your six-digit grid square location properly. Other hams can use this to log your contact to the proper location for their contest or to calculate the beam heading so they or their computer can swing their beam directly to your shack.

Digital modes and logging systems use grid squares to calculate the distance between your station and the person you are talking to. Some of these systems use the distances to help calculate propagation and report signals as ‘beacons’ to others to predict propagation paths.

Find Your Grid Square

There are many online ways to find grid squares. My favorite site is the Amateur Radio Ham Radio Maidenhead Grid Square Locator Map (levinecentral.com). You can enter a four or six-digit grid square on this site, and a map of that location will appear on the screen. You can also enter an address, city, and state, and the system will calculate the grid square of that location and provide a map. And you can enter an amateur radio callsign, and the system will look up the grid square assigned to that callsign and display a map of that location. It’s handy to keep this web page open when you are making contacts to see where the other person lives.