The online coordinate converter converts coordinates in a range of datums, projections and height systems used in New Zealand. It also allows a variety of input and output formats.
Using the coordinate converter
Before converting coordinates you must select the coordinate system and format of the input and output coordinates. If the coordinate conversion depends on the date of the coordinates (for example if it uses the deformation model) then you must also supply a date.
The coordinate system can be selected either by entering its name in the search box - for example "eden" - or by selecting from the drop down list beneath it. The search box also recognizes codes such as nztm and wgs84.
Each coordinate system can also have an associated height coordinate system - the converter can convert both horizontal and vertical coordinate systems.
The coordinate format includes options for associating an identifying name with each point, choosing the order of east and north (or longitude and latitude) coordinates, and the character used to separate the coordinates that you input. As you select these you can see an example of the coordinate input (or output) format to confirm it is what you want.
Tip: The converter has a link to several commonly used conversions. You can use these directly or customise them, for example to change the coordinate format
Tip: If you have input coordinates and are not sure what coordinate system or format to use try clicking the Not Sure? button. This will take you to a page where you can enter an example coordinate and the converter will guess its coordinate system and format.
Tip: If you are just converting between between different vertical datums use the simpler vertical datum converter. This converts between vertical datums such as the New Zealand Vertical Datum 2016 and local mean sea level datums.
Once you have selected these options click the Enter coordinates button to go to the coordinate entry page where can enter one or more coordinates to convert. If you have a large number of coordinates you can copy and paste them into the converter. The converted coordinates can either be displayed in your browser or downloaded.
Tip: If you are likely to do the same conversion again in the future you can bookmarks the coordinate entry page to reuse it. This will save all the settings you used for the conversion into the bookmark.
Date required for some transformations
Some transformations require specifying a date at which the transformation applies. This is because New Zealand is moving across the earth at about 5cm per year due to plate tectonics. The New Zealand coordinate systems such as NZGD2000 and NZTM are moving with it, whereas the global coordinate systems such as the WGS84 and ITRF realisations are not. The relationship between them changes over time and so to convert between them requires knowing the date at which the conversion is to apply.
Generally the date will be that at which the coordinates were measured. For lower accuracy requirements using the correct date is not critical. Generally the relationship only changes at around 5cm per year. More significant changes happen when coordinates are affected by earthquakes.
Dates can be entered in a number of formats, such as a decimal year (2016.5) and day month year (25 June 2016). Alternatively the word “now” can be used to apply the transformation for the current date.
Many transformations do not require a date (for example from NZGD2000 to NZTM), and for these the date can be left blank.
Multiple versions of WGS84
Often coordinates are misidentified as WGS84. In fact there are many versions of WGS84 and so converting accurately between WGS84 and other datums requires knowing what version of WGS84 applies. Also in many cases coordinates are labelled as WGS84 when they are actually in terms of other datums, such as ITRF2008 or NZGD2000.
About datums and projections
Read more about NZGD2000 (New Zealand Geodetic Datum 20000), WGS84 (World Geodetic System 1984), NZMG (New Zealand Map Grid) and NZTM2000 (New Zealand Transverse Mercator 2000) on the Datums, Projections & Heights page.