Height Conversions

This page provides information on height conversions, including resources to more in-depth information.

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 NZVD2009 and 13 local mean sea level 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 NZGeoid2009 as a transformation surface (and also an offset if required). The general relationship between the different datums is shown in the figure below.

This diagram shows the general relationship between the different datums