Grid Square Products

1km Grid Square

The 1km Grid Square product provides basic 2001 Census statistics (population and household counts) for 1km grid squares in Northern Ireland based on grid references.  An explanation of the grid square references is available.

Attribute Table - 1km Grid Square

The attribute table includes a grid square reference (GridSq), population and household counts from the 2001 Census in each Grid Square, and geographic coordinates for easting (X) and northing (Y).

Irish Grid & Grid Square References

Grid Squares are made up of a system of squares defined by two lines at right angles to each other.  The first, called the easting, is an east to west line that runs parallel to the central meridian while the second, called the northing, runs at right angles to it.  Grid Squares are zero referenced at the far southwest of Ireland and both the easting and northing are calibrated in metres.

The area of Ireland is divided into 20 squares, measuring 100km by 100km, each identified by a single letter.

Grid Square references are made up of a combination of the easting and northing and consist of a letter and an even number of digits.  The letter designates one of the twenty 100 kilometre squares that cover Ireland, as shown by the map above.  The remaining numbers represent a point within that 100 kilometre square by giving the distance east and north from the bottom southwest corner of the square.  The numbers can vary in numbers of digits depending upon the resolution of the grid reference.

For example:  Belfast City Hall has an easting 333831 and northing 374015 which means it is 333831 metres east and 374015 metres north of the bottom southwest corner.  This puts it in 100km square J.  The distance from the southwest corner of square J is 33 831 metres east and 74 015 metres north.  The grid reference of the City Hall is thus J 33 74 to a 1km resolution and J 338 740 to a 100m resolution.

Census Office Grid Squares

The grid-squares used for Census purposes uses this grid reference to refer to the area enclosed by a square projected from that grid reference by the distance that the resolution of the grid reference dictates.  Thus a grid-square with reference J 33 74 extends 1km east and 1km north from that point while the grid-square with reference J 338 740 extends 100m east and 100m north.

Easting and Northing point references

A grid reference for a point location is made up of a combination of the easting and northing from this location.

For example: Belfast City Hall has an easting 333831 and northing 374015 which means it is 333831 metres east and 374015 metres north of the bottom southwest corner.  The Giants Causeway has an easting 294724 and northing 444769 which means it is 294724 metres east and 444769 metres north of the bottom south west corner.   Finally Enniskillen Castle has an easting 223141 and a northing 344221.

Creation of Combined Grid Product

In large settlements 100 metre grids replace 1kilometre grids to give greater resolution of population and household statistics.  

The settlement development limits (SDLs) used were those as defined by the Planning Service.

In total over 100 settlements in Northern Ireland have a population of greater than 1000 people (2001 Census). The images on the right outline the various stages in creating a combined 100 metre and 1 kilometre grid-square file.

STAGE 1: SDLs and 1Km grids are used to determine the creation of 100m grids.

STAGE 2:  1Km grids that contain part or all of an SDL are selected to be replaced by one hundred 100 metre grids.

STAGE 3: 100 metre grids replace whole 1Km grids for 118 settlements in Northern Ireland.