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All About Grid Squares?

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Call Book


What are Grid Squares or Maidenhead Locators? - The basics

We all know and understand co-ordinates given in degrees minutes and seconds using latitude and longitude. These co-ordinates are good and very accurate but tedious to relay by radio.

This is where grid squares come in. Very basically, grid squares are very small rectangles calculated from your normal latitude and longitude co-ordinates. The normally consist of a combination of six letters and numbers. ie. KF37wa

This six character combination is simple and quick to relay over the radio. Its not quite as precise are the normal co-ordinates given in degrees minutes and seconds, but is accurate enough for amateur radio contest or award requirements.

What are Grid Squares or Maidenhead Locators? - A bit more detail

The "Maidenhead QTH Locator System" is the official QTH locator system adopted by the IARU (International Amateur Radio Union) and replaces the old "QRA Locator System". The new system is used primarily by the Amateur Radio Service and uniquely defines any given point on the surface of the globe to within an area of 5 minutes of longitude by 2.5 minutes of latitude. This is achieved using a six character reference, although this can be extended to eight characters, with a corresponding increase in resolution.

Some GPS (Global Positioning System) receivers can be programmed to display Maidenhead QTH Locators directly. The main disadvantage of the old QRA Locator System was that several points on the earth's surface had the same reference. When first introduced, this did not present a problem, but as the equipment and operating techniques improved, so did the ranges achieved, which gave rise to possible ambiguities.

The Grid Locator System is primarily used on the VHF bands, the six character groups
forming part of contest exchanges. They are also often used during normal QSOs to
pin-point a stations location. There is also considerable interest in "collecting
squares" (the first four characters of the Grid square, e.g. KF37).

How big is a Grid Square?

To answer that properly we must break down the Grid Square into three parts. We'll use KF37wa as and example.

  • The first two characters represent a rectangular area 20 wide and 10 high. KF
  • If we include the two numbers next the rectangle becomes 2 wide and 1 high. KF37
  • Once we include the last two letters the rectangle becomes very small and represents only 5.5km x 5km. KF37wa

How can I calculate my locator?

Very easily, simply use the calculator below to do all the hard work for you. Once you know your grid locator you can add it to the national database by looking up your callsign in the online call book and then adding your Grid Locator from there.

Latitude (dms)
Longitude (dms)
IARU Locator
Display locators with characters.

Copyright 1997- 2006South African Radio League
Last modified: 20 April 2004