M.J.Harley's
Sundials in Ireland Website

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The Irish Grid System

The Primary Irish Grid covers the country with a pattern of squares which have 100 kilometre (100,000 metres) sides. Each square is identified by a unique letter.

Grid references consist of a number of digits made up of Eastings and Northings, Eastings being quoted first. For example the most Northerly point in Ireland, Malin Head, has full Irish Grid co-ordinates of 239873m East and 459924m North which locate it to the nearest metre. The use of the square letter in grid references is optional. When the letter is used the first digit of both co-ordinates (the ones which locate the appropriate square) are dropped, Malin Head can therefore also be located by grid reference C 39873 59924

The number of digits in a grid reference depends on the scale of the map being used, the Primary Grid being further sub-divided on maps as follows :-
Maps at 1:500 000 and 1:250 000 scale have 10 kilometre squares. Malin Head can be found on these maps by first locating the square 23 East and 45 North. And then by measurement or visual estimation from the South West corner of the square go a further 9km East and 9km North. This will locate Malin Head to within 1km. The grid reference being 239 459 or C 39 59

Maps at 1:100 000, 1:50 000, 1:25 000 and 1:10 000 scale have 1 kilometre squares. Malin Head can be found on these maps by first locating the square 39 East and 59 North. And then by measurement or visual estimation from the South West corner of the square go a further 800m East and 900m North. This will locate Malin Head to within 100m. The grid reference being 2398 4599 or C 398 599

Maps at 1:2500 and 1:1250 scale have 100 metre squares. Malin Head can be found on these maps by first locating the square 398 East and 599 North. And then by measurement or visual estimation from the South West corner of the square go a further 70m East and 20m North. This will locate Malin Head to within 10m. The grid reference being 23987 45992 or C 3987 5992


Malin Head's (239873m East and 459924m North) map reference at each scale is as follows:-

Map Scale Square Size Grid Reference with square letter Grid Reference without square letter
1:500 000
1:250 000
10Km C 39      59 239      459
1:100 000
1:50 000
1:25 000
1:10 000
1Km C 398    599 2398    4599
1:2500
1:1250
100m C 3987  5992 23987  45992