The NGS Geoid Page

NOTICE: NGS Update, September 11, 2012

GEOID12A Model Released

The National Geodetic Survey has released the GEOID12A model. Analysis of the underlying control data has been completed and a number of corrections were made to the original data used in making GEOID12. Changes impacted regions in the states of Alabama, Mississippi, Louisiana, Texas, Oklahoma, and Wisconsin. GEOID12A is now available for production and use.


The National Geodetic Survey has released updated models for transforming heights between ellipsoidal coordinates and physical height systems that relate to water flow. These models cover regions including the conterminous United States (CONUS), Alaska, Hawaii, Guam and the Commonwealth of the Northern Mariana Islands, and American Samoa. Models for Puerto Rico and the U.S. Virgin Islands are being held back pending release of final control data for the USVI but will likely be released later this Fall. GEOID09 transforms to NAVD 88 in CONUS and Alaska and to the respective datums for all the other regions (each having its own datum point). Models for the Deflection of the Vertical have also been released for these same regions mainly for aid in navigation systems.

Latest models

Hybrid Geoids

Converts heights from NAD 83 to regional Vertical datums
(e.g., NAVD 88)

Gravimetric Geoids

Converts heights from ITRFxx to the NGS geoid surface
(not NAVD 88 or other Vertical datums)

Hybrid Vertical Deflection Models

Gravimetric Vertical Deflection Models


Geoid Frequently Asked Questions


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