# Converting between NZVD2016, NZGD2000 and local vertical datums

This page holds information regarding conversion between NZVD2016, NZGD2000 and local vertical datums.

The two height systems used in New Zealand are normal-orthometric and ellipsoidal. Normal-orthometric heights refer to the Earth’s gravity field and include the NZVD2016 and 13 local vertical datums. Ellipsoidal heights refer to a geometric figure approximating the Earth (an ellipsoid) and include the NZGD2000 and GNSS/GPS receivers.

Heights can be converted between datums using NZGeoid2016 as a transformation surface (and also an offset if required). The general relationship between the different datums is shown in the figure below.

Use the equations below to convert:

• NZGD2000 (ellipsoidal) to NZVD2016 (normal-orthometric)
• Local vertical datums to NZVD2016 (normal-orthometric)
• Local vertical datums (normal-orthometric) to NZGD2000 (ellipsoidal).

Alternatively, use the advanced online conversion tool. Read instructions for carrying out height conversions.

### NZGD2000 ellipsoidal to NZVD2016

The NZGeoid2016 model can be used to transform heights between the NZGD2000 and NZVD2016 datums:

• Determine NZGD2000 coordinate (latitude, longitude) and ellipsoidal height (h) for point to be converted
• Determine NZGeoid2016 value (N) by interpolating the grid at the above coordinate. This can be computed online or by downloading the NZGeoid2016 model
• Use the following equation to determine the NZVD2016 height ( HNZVD).

HNZVD= h – N

### Local vertical datum to NZVD2016

The NZGeoid2016model can be used to transform heights between the 13 local vertical datums and NZVD2016:

• Determine NZGD2000 coordinate (latitude, longitude) and local vertical datums height (HA) for point to be converted
• Determine NZGeoid2016 value (N) by interpolating the grid at the above coordinate. This can be computed online or by downloading the NZGeoid2016 model
• Determine the offset (oA) for the input local vertical datum. This can be computed online or by downloading the appropriate local vertical datum relationship grid.
• Use the following equation to determine the NZVD2016 height ( HNZVD).

HNZVD= HA - oA

### Local vertical datum to NZGD2000

The NZGeoid2016 model can be used to transform heights between the 1 local vertical datum and the NZGD2000:

• Determine NZGD2000 coordinate (latitude, longitude) and local vertical datum height (HA) for point to be converted.
• Determine NZGeoid2016 value (N) by interpolating the grid at the above coordinate. This can be computed online or by downloading the NZGeoid2016 model
• Determine the offset (oA) for the input local vertical datum. This can be computed online or by downloading the appropriate local vertical datum relationship grid.
• Use the following equation to determine the NZGD2000 height (h).

h= HA + N - oA

Last Updated: 6 August 2020