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North and South Island Yard Grids (NIYG, SIYG)

The North Island Yard Grid and South Island Yard Grid were the projections for the 1:63,360 (inch-to-the-mile) topographic mapping in New Zealand between 1942 and 1973.

Between 1942 and 1973, mainland New Zealand’s inch-to-the-mile (1:63,360) topographic maps were created using the North Island Yard Grid and South Island Yard Grid projections. These were based on imperial units, including the yard (.9144 meters).

The New Zealand Yard Grid was established to provide a consistent and standardized way of mapping and surveying across the country. It was used for New Zealand Map Series 1 (NZMS1), a range of map sheets covering the country in areas of 1° latitude by 2° longitude.

The North Island Yard Grid and South Island Yard Grid projections were replaced when the metric system was introduced. They were superseded by New Zealand Map Grid (NZMG) and later New Zealand Transverse Mercator (NZTM2000).

The yard grids may still be referenced in older databases.

Find out more about projections

The key parameters of the NIYG are summarised below
NameNorth Island Yard Grid
AbbreviationNIYG
EPSG number27291
Projection typeTransverse Mercator
Reference ellipsoidInternational 1924
DatumNew Zealand Geodetic Datum 1949 (NZGD1949)
Origin latitude39° 00' 00" South
Origin longitude / central meridan175° 30' 00" East
False Northing400,000 yards North
False Easting300,000 yards East
Central meridian scale factor1.0000
The key parameters of the SIYG are summarised below
NameSouth Island Yard Grid
AbbreviationSIYG
EPSG number27292
Projection typeTransverse Mercator
Reference ellipsoidInternational 1924
DatumNew Zealand Geodetic Datum 1949 (NZGD1949)
Origin latitude44° 00' 00" South
Origin longitude / central meridan171° 30' 00" East
False Northing500,000 yards North
False Easting500,000 yards East
Central meridian scale factor1.0000
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