NZVD2009 Datum Offsets

The 13 mean sea level (MSL) datums used in New Zealand are offset from the New Zealand Vertical Datum 2009 (NZVD2009) and each other. This is because the datums are defined in terms of mean sea level at their respective standard ports. The relationship of the different height surfaces is shown in the figure below.

NZGeoid05 was replaced by the New Zealand Quasigeoid 2009 (NZGeoid09) in September 2009. The New Zealand Vertical Datum 2009 (NZVD2009) uses NZGeoid09 as its reference surface.

The offsets from the NZVD2009 reference surface (NZGeoid09) to each of the MSL datums are provided below. The offset is positive when NZGeoid09 is above the levelling datum.

MSL Datum	NZGeoid09 Offset (metres)	Standard Deviation (metres)
One Tree Point 1964	0.06	0.03
Auckland 1946	0.34	0.05
Moturiki 1953	0.24	0.06
Gisborne 1926	0.34	0.02
Napier 1962	0.20	0.05
Taranaki 1970	0.32	0.05
Wellington 1953	0.44	0.04
Nelson 1955	0.29	0.07
Lyttelton 1937	0.47	0.09
Dunedin 1958	0.49	0.07
Dunedin-Bluff 1960	0.38	0.04
Bluff 1955	0.36	0.05
Stewart Island 1977	0.39	0.15

These offsets can be used in conjunction with NZGeoid09 to transform NZGD2000 ellipsoidal heights to normal-orthometric heights in terms of the MSL datums.