Transformations between WGS84 and NZGD2000

Transforming coordinates between the World Geodetic System 1984 (WGS84) and New Zealand Geodetic Datum 2000 (NZGD2000) is more complex than some other transformations as a reference date is required for WGS84.

The World Geodetic System 1984 (WGS84) is a dynamic datum. Its coordinates change with time, and the datum has many different versions (or realisations). This means that an accurate transformation using WGS84 is only possible with a reference date. This is usually stored as the coordinate epoch.

World Geodetic System 1984 (WGS84)

Geodetic datums

Coordinate systems used in New Zealand

Geodetic datum conversions

When you are calculating a coordinate transformation that includes a ground-fixed datum, additional parameters are needed to account for the time-dependent transformation and its deformation model/distortion grid. These provide the parameters for the internal deformation of the datum.

True WGS84 coordinates

Before converting WGS84 coordinates, it is important to confirm the data is WGS84 as opposed to it being in terms of a datum such as NZGD2000. The metadata and supporting documentation will show how the coordinates were calculated. Most coordinates in New Zealand are Zealand Geodetic Datum 2000 (NZGD2000) as they have been observed relative to a known geodetic mark. 

Trig stations and geodetic marks

It has been common practice to assume that NZGD2000 and WGS84 are the same for most practical purposes (such as navigation). The Standard for New Zealand Geodetic Datum 2000 (effective 16 November 2007) describes WGS84 and NZGD2000 coordinates as 'identical, at the 1m level'. This is true, if not sufficient when accuracies better than 1m are required.

Find out more about WGS84 coordinates

Online coordinate conversions

Our online coordinate converter includes time-dependent transformations to and from WGS84.

Online coordinate converter

Guidelines for coordinate transformation for when the time of the WGS84 data is unknown are shown in the following table.

WGS84 coordinate accuracySuggested actions/required information
Less than 0.2mTo maintain the accuracy of the data, the correct realisation/version and coordinate epoch (time to the nearest day) is required. If this is not available, additional fieldwork can be used to check the coordinates to confirm the datum epoch.
Between 0.2m and 2m

To achieve this level of accuracy, the process is as above, except:

  • specifying the realisation of WGS84 is not essential, and
  • the coordinate epoch can be approximate (to the nearest year).

If the data is from a region affected by a significant earthquake, the coordinate epoch needs to indicate whether the data is pre- or post-earthquake.

More than 2m

No transformation required.

At this level of accuracy, we can assume WGS84 coordinates are the same as NZGD2000 until 2040.


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