NADCON computations

Use NADCON (North American Datum Conversion) to convert latitude and longitude from NAD 27 to NAD 83 or from NAD 83 to NAD 27.

Computations may be performed for a specific geographical location or for a file of input points.

Compute a datum shift for a specific location:

Select direction of conversion:


The three formats below may be used for entering latitudes and longitudes.The latitude and longitude must both be positive and will be interpreted as north latitude and west longitude. Degrees, minutes and seconds may be separated by spaces or commas.

Enter Latitude:

Enter Longitude:

Enter Station Name (optional)

Compute NADCON datum shifts for a file of input points:

Select direction of conversion:

There are three choices of input format. Each input format has a corresponding file output format, most of which are text files suitable for further processing. You may use the SaveAs function of your browser to save this file to your computer. In addition, you may choose formatted and labelled output, irrespective of the input format. Input records that contain an invalid latitude or longitude are skipped in the file output. Error messages are written to the formatted and labelled output.

Select an Input Format:
Free Format 1 [explain]
Free Format 2 [explain]
BlueBook format [explain]

Specify the input file (on your computer)

Choose the type of output desired:

Output file format corresponding to the input file format (not available for Free Format 1)
Formatted and labelled output, suitable for printing