Updated: 28 June 2005

Parameters for commonly used Ellipsoids

Ellipsoid Parameters	Ellipsoid Name	"165"	ANS	CLARKE 1858	GRS80	WGS84	WGS72	International 1924
Major Semi Axis	a	6378165.000	6378160.000	6378293.645	6378137	6378137	6378135	6378388
Inverse Flattening	1/f	298.3	298.25	294.26	298.2572221	298.2572236	298.26	297
Flattening	f = 1 / f	0.003352330	0.003352892	0.003398355	0.003352811	0.003352811	0.003352779	0.003367003
Minor Semi Axis	b = a * ( 1 - f )	6356783.287	6356774.719	6356617.938	6356752.314	6356752.314	6356750.520	6356911.946
Eccentricity	e	0.081813334017	0.081820179996	0.082372092204	0.081819191043	0.081819190843	0.081818810663	0.081991889979
Eccentricity squared	e2=2f-f2=(a2-b2)/a**2	0.006693421623	0.006694541855	0.006785161574	0.006694380023	0.006694379990	0.006694317778	0.006722670022
Second Eccentricity	e'	0.082088521821	0.082095437120	0.082652976376	0.082094438152	0.082094437950	0.082094053920	0.082268889607
Second Eccentricity squared	e'2=e2/(1-e2)=(a2-b2)/b2	0.006738525415	0.006739660796	0.006831514504	0.006739496775	0.006739496742	0.006739433689	0.006768170197

For more information contact: geodesy@ga.gov.au