Skip to content



Tweaks and Updates to US National Geodetic Survey NADCON5 Tool. Used to calculate transformation between various US Datums, including: US Standard Datum (USSD) used prior to NAD27, North American Datum of 1927 (NAD27), and various realizations of the North American Datum of 1983 NAD83

Build the dataset with one command


Link To Doxygen Documentation Website Link To the Python Library Documentation


The intent of this project is to adapt the existing tool to be accessible to more users, through the implementation of additional interfaces and workflows on top of the existing NADCON5 Code Base and Data

NOTE: This project is a private project that is not in any way affiliated with the US Government, NOAA, or the National Geodetic Survey

Derivative Work: Additions and Modifications to NADCON5 code, documentation source files, and the source code of nc5ng-core python package are released explicitly into Public Domain where applicable, with no rights reserved in perpetuity. However, certain published outputs associated with this project, e.g. builds and compiled documentation may be release under other licenses, Please see Licensing Section below.

Creative Commons License

Project Status

This project is new, feature requests and development will be driven through issues filed in github.

At the time of this README was updated, the following was true

  1. GNU Make Pipeline: The existing processing pipeline has been offloaded to GNU Make to eliminate in-source builds
  2. Documentation: Documentation generation via Doxygen is functioning
  • Doxygen was bootstrapped on top of the NADCON5 code to create compiled documentation
  • Fortran source files were modified, superficially, to export documentation in a doxygen format
  • hosted online at url:
  1. Python package: Initial Framework for a python glue library
  • Functioning f2py submodules and functions
  • Data Inspection library and bundled source data
  • install with pip install nc5ng-core (Requirements: gfortran)
  • Rudimentary GMT/Python integration
  • Plotting NADCON5 input and output data directly through python wrapper

On the Immediate Roadmap

  1. Remove build dependence on proprietary Oracle Fortran f95
  • Requires mapping build options to gfortran and correcting where necessary
  • Biggest issue is compiler specific handling of I/O and certain convenience extensions, not the math
  • n5ng-core already uses gfortran for f2py
  1. Take over the "batch" programs (e.g. makework() , makeplotfiles01 , etc.) so that individual conversions can be done as needed, through Make or nc5ng-core

What is NADCON5?

NGS NADCON5 Front Page


The Following Information is Reproduced from the NADCON5 Webpage from NGS

What is NADCON 5.0?

NADCON 5.0 performs three-dimensional (latitude, longitude, ellipsoid height) coordinate transformations for a wide range of datums and regions in the National Spatial Reference System. NADCON 5.0 is the replacement for all previous versions of the following tools:

  • NADCON, which transformed coordinates between the North American Datum of 1927 (NAD 27) and early realizations of the North American Datum of 1983 (NAD 83), and
  • GEOCON, which transformed coordinates between various latter realizations of NAD 83.

How do I use NADCON 5.0?

NADCON 5.0 is functionally implemented in NGS’s Coordinate Conversion and Transformation Tool. Unlike earlier versions of NADCON and GEOCON, NADCON 5.0 is not a stand-alone tool.

Visit the NADCON 5.0 Digital Archive to access raw transformation data that make up NADCON 5.0 (e.g., grids, images, software).

How can I learn more about NADCON 5.0?

NOAA Technical Report NOS NGS 63 (PDF, 17 MB) provides detailed information on NADCON 5.0, and the digital archive includes plots and data.

Building NADCON5-ng

Build simply with


Which will build the initial tools and generate conversion output and images for the configured conversion


  1. Generic Mapping Tools **GMT**

    • Tested with 5.2.1
    • Install on Debian Systems with sudo apt-get install gmt gmt-dcw gmt-gshhg
  2. Oracle Fortran (f95) available for free (as in money, but not freedom) in Oracle Developer Studio

  3. GNU Make

Build Options

The configurable options for the build steps are

  1. OLD_DATUM - source datum (default: ussd)
  2. NEW_DATUM - target datum (default: nad27)
  3. REGION - geographical region (default: conus)
  4. GRIDSPACING - Grid Spacing in arc-seconds (default: 900)
  5. MAP_LEVEL - Map Resolution Flag (default: 0)

These can be set as environment variables or directly on the command line

export OLD_DATUM=nad27
export NEW_DATUM=nad83
# Equivalent
OLD_DATUM=ussd NEW_DATUM=nad27 make
# Third Option
make OLD_DATUM=ussd NEW_DATUM=nad27


The Upstream build sequence can be simulated by using the targets doit doit2 doit3 doit4, as in

make doit
make doit2
make doit3
make doit4

This can be useful to compare results from the vanilla NADCON

Additionally, for the intermediate scripts gmtbat0X convenience targets are provided to manually step through the asset compilation

make gmtbat01
make gmtbat02
make gmtbat03
make gmtbat04
make gmtbat05
make gmtbat06
make gmtbat07

Cleaning up is easy

Delete only the current configured build

make clean

Delete all compiled output (deletes build directory)

make mrclean

Licensing {#s-license}

A work of the US Government, the original NADCON5 Source Code and Data is considered in the public domain within the United States of America. Elsewhere, the US Government may reserve copyright and license this material. The licensing status of the NADCON5.0 source material outside of the US is not clear to the authors of NADCON5-ng . The authors and contributors cannot offer advice in this regard.

The licenses governing the derivative works provided by and its contributors are enumerated below.

Public Domain

New contributions, including:

  • Any modifications to National Geodetic Survey NADCON5.0 source code or data by nc5ng contributors
  • Makefile and build system
  • Documentation files and new documentation embedded in source files
  • Source code for python packages nc5ng.core and nc5ng.nc5data

Are released explicitly into the public domain in the United States and internationally as much as is allowed by law. The license file LICENSE states the terms of the Creative-Commons CC0 public domain disclaimer.

Creative Commons License

Fallback License

The fallback MIT License should be used in all cases where public domain release is not recognized or not applicable. A copy is provided with the distribution in the file LICENSE-MIT

Compiled Assets generated by and contributors

Compiled assets are published works generated using NADCON5-ng or in association with the project and usually published seperately from the public domain source code. For example, to promote the project or support the user base.

Compiled works are occasionally released in association with this project, This includes:

  • Pre-compiled HTML and PDF documentation and live webpages
  • Printed documentation provided by
  • Pre-compiled and pre-processed output data provided by
  • Websites, bug reports, project planning pages, and related project pages.

Compiled assets published by are provided with rights reserved and will default to a Creative Commons Attribution 4.0 International License, unless a different license is specified in the work.

Creative Commons License