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.