Computation of GEOID18 Geoid Height


A GEOID18 geoid height can be computed for a specific geographic location or for a file of input points. Position coordinates should be in the appropriate North American Datum of 1983 (NAD 83) reference frame.

GEOID18 will compute geoid heights for the following geographic areas:

Area Ellipsoid Reference Frame Vertical Datum Latitude Longitude
Min Max Min Max
Conterminous United States NAD83 (2011) NAVD88 24N 58N 60W 130W
Puerto Rico and U.S. Virgin Islands NAD83 (2011) PRVD02 and VIVD09 15N 21N 64W 69W

Users in Alaska, Hawaii, Guam and the Commonwealth of the Northern Mariana Islands should continue to use GEOID12B.


Compute a GEOID18 geoid height for a single location:

The formats below may be used for entering latitude and longitude. Degrees, minutes, and seconds must be separated by spaces. (Note that commas are not valid for GEOID18 computations.)

Degrees, minutes, and decimal seconds
Latitude Example: 35 55 19.0221
Longitude Example: 97 55 40.2351
Degrees, minutes, and integer seconds
Latitude Example: 35 55 19
Longitude Example: 97 55 40
Degrees and decimal minutes
Latitude Example: 35 55.3453
Degrees and integer minutes
Latitude Example: 35 55
Decimal degrees.
Latitude Example: 35.9320
Integer degrees.
Latitude Example: 35

Enter Latitude:

Enter Longitude: West East


Compute GEOID18 geoid heights for a file of input points:

There are three types of input formats you can use. Each input format has a corresponding output format, most of which are text files suitable for further processing. You may use the "SaveAs" function of your browser to save the output file to your computer.

Choose an input format:

Free Format Type 1 [explain]
Free Format Type 2 [explain]
NGS Blue Book (*80* and *86* records) format [explain]

Specify the input file (on your computer)

Specify the longitude convention for your file: Positive West Positive East


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Questions or comments on this page?

Send e-mail to NGS Geoid Team.