Maidenhead Locator

55.000000
-10.000000

The map

  • You can enter 2, 4, 6 or 8 digits, e.g IO, IO66, IO66ML or IO66ML98
  • 2 digits will bound 20° of longitude and 10° of latitude.
  • 4 digits will bound 2° of longitude and 1° of latitude.
  • 6 digits will bound 5' of longitude and 2.5' of latitude.
  • 8 digits will bound 30" of longitude and 15" of latitude.
  • The longitude and latitude values displayed represents the centre of the bounding box, where there is a marker.

Maidenhead locator system

The Maidenhead locator system uses alternative pairs of letters and numbers:

  • In each pair the first character represents longitude, the second character latitude.
  • The first pair (field) represent longitude & latitude in base 18 using letters A to R which equates to 20° of longitude and 10° of latitude.
  • The second pair (square) are in base 10 using numbers 0 to 9 which equates to 2° longitude and 1° of latitude.
  • The third pair (subsquare) are in base 24 using letters A to X which equates to 5' (0.08333333°) longitude and 2.5' (0.04166667°) of latitude.
  • The fourth pair (extended square) are in base 10 using numbers 0 to 9 which equates to 30" (0.00833333°) of longitude and 15" (0.00416667°) of latitude.
  • In order to avoid the use of negative numbers, latitude values range from 0° at the south pole to 180° at the north pole. Longitude values range from 0° at the Greenwich anti-meridian to 360°, i.e the Greenwich meridian is represented by 180°.
  • Note: The correct way to write a Maidenhead locator is with ALL the letters in upper case. The old QRA system used lower case letters in the third field, e.g. IO91ab and this format has been erroneously used in many Maidenhead software packages over the years.