How to Convert the Latitude & Longitude to NAD 27 & NGVD 29

You can describe a geographic point on the Earth in many different ways. Latitude and longitude coordinates, for instance, use the Equator and the Greenwhich Meridian as reference points to describe all other points on the earth in terms of their distance from the references. Systems like the North American Datum (NAD) or the National Geodetic Vertical Datum (NGVD) use smaller imaginary polygons and regional references to achieve more precise data points in a limited area of the planet -- in this case, North America and the United States. More precise local coordinate systems such as NAD and NGVD use their own geometry. This means that to convert from latitude and longitude, you must recalculate all of the arcs used in the measurement -- a very complicated process. Fortunately, you can also use specialized geographic calculators, provided by universities and the U.S. National Oceanic and Atmospheric Administration (NOAA), to more easily convert latitude and longitude measurements to NAD and NGVD coordinates.

Things You'll Need

• Latitude and longitude coordinates
• Computer with Internet access

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Instructions

1. • 1

     Access an online latitude and longitude-to-Universal Transverse Mercator (UTM) calculator. A number of universities, including Montana State University, provide online applications. The most recognized application is provided directly from the NOAA.

   • 2

     Select the kind of data you are entering from the drop-down list or toggle box options in the applet. If you are entering standard latitude and longitude data in degrees, minutes and seconds, for example, select the "Latitude and Longitude DMS" options.

   • 3

     Fill in all the information you have on your latitude and longitude coordinates. Be as precise as possible, including minutes and seconds after your degree values.

   • 4

     Select the kind of data you want to receive after the conversion, such as NAD27, NAD83, NGVD 29 or any other UTM system.

   • 5

     Click on the convert button or press "Enter." The applet will do all of the calculations and return a value in the selected measurement system.