Gtrans is a program for performing coordinate transformations. On this page, you can read more about the software and download it.

About the software

Logotype of Gtrans 4Gtrans is a software for transforming coordinates for geodetic and cartographic purposes. Current transformations between Swedish national and regional coordinate systems are included in the installation. Users can also create and add custom transformations and coordinate systems.

The program can read the file formats csv, k-file and lua. Users can program their own plugins to read and write additonal formats.

Gtrans is designed for transformations and calculations to be performed with correct algorithms and with sufficient precision.The program is developed by the Geodesy department at Lantmäteriet, but has also been widely distributed outside Lantmäteriet.

The computation core of Gtrans can be built into other programs or systems.

Gtrans is available also in other languages than Swedish. The language of the operative system controls the language of the software.

Download Gtrans

Gtrans may be used free of charge for any purpose. Lantmäteriet strives to make the program as good as possible but takes no responsibility for any errors.

Lantmäteriet renounces all responsibility for this software being free from interruptions, safe or free from errors. Lantmäteriet cannot be held responsible for any damages arising from the use of this software. Any use of this application is at the user's own risk.

You can subscribe to news about Gtrans if you want to receive emails when new, improved versions of the program is released. In that way you will not miss any information about e.g. bug corrections.

Version history

Differences between versions 4.1.1 and 4.1

  • When doing an estimation, it is possible to create a report when the new conversion is stored in the database.
  • When a height conversion is added to a conversion to/from ITRF, the name of the conversion is now correct.
  • When Gtrans is started in another language than Swedish or English, the program does not crash.

Differences between versions 4.1 and 4.0, in brief

  • Improved functionality in the estimation module. Among other things, the residual error vectors are plotted correctly and the map support has been updated. Estimations are iterated until convergence is achieved so that the fitting result is correct and there is a possibility of searching for outliers among estimation points. It is possible to print a report with the estimation results and to export the created transformation to a file.
  • Improved plugins for importing and exporting CSV  and k files.
  • Bug fixes and smaller improvements in functionality.
  • Gtrans is also available in English; the user interface as well as user manual and report of the estimation result. The language of the operative system controls the language of the software.
  • The installation package is signed with Lantmäteriet as the verified publisher.

Older program versions

For a long time until version 4.0 was released in 2022, version 3.63 of Gtrans was the most recent version. If you for some reason need to download Gtrans 3.63, contact the Geodesy department. However, we recommend that you choose the latest version of Gtrans 4.

Support and courses

A user manual is included with the installation and describes the basic functionality of the program. You can find it by choosing Application > User guidelines in the program. If you have further questions, contact the Geodesy department.

Training in the program is included as part of the course package Koordinatsystem och Gtrans (taught in Swedish).

E-service for coordinate transformation

You can also transform individual coordinates in Coordinate Transformation e-service that supports the newer Swedish national coordinate and height systems.

Questions and answers

In Gtrans, transformations are organised in databases. Two databases are included in the default installation:

SWEREF_99+RH_2000.gdb containing

  • transformations between SWEREF 99 lat/long, geocetric Cartesian coordinates, SWEREF 99 TM and the local SWEREF 99 projection zones,
  • the geoid model SWEN17_RH2000 for transformation between ellipsoidal height and RH 2000.

SWEREF_99+RH_2000+RT+ITRF.gdb containing

  • all the transformations mentioned above,
  • the geoid model SWEN17_RH70 for transformation between ellipsoidal height and RH 70,
  • the preceding geoid models SWEN08_RH2000 and SWEN08_RH70,
  • transformations between RT 90 and SWEREF 99, with and without residual surface,
  • transformations between RT 90 lat/long and the six projection zones,
  • transformations between the regional systems (RT Rnn) 2.5 gon V and RT 90 2.5 gon V, with and without residual surfaces,
  • transformation between RT 38 2.5 gon V and RT 90 2.5 gon V, with residual surface,
  • transformation between ITRF2014 and SWEREF 99.

Yes. You can import tf and tfi files to your database in Gtrans 4. To do this, choose Database > Import conversions.

However, it is not possible to export tf or tfi files from Gtrans 4.

If the transformation requires multiple steps (e.g. from SWEREF 99 16 30 to lat/long, then on to RT 90 2.5 gon V), Gtrans can automatically create a transformation chain given that all steps are included in your database.

If a transformation step is missing you will need to add it, e.g. by creating it yourself through an estimation or by assigning transformation parameters. You can also import a lua or tf file.

By default, Gtrans displays latitudes and longitudes as degrees, minutes, and seconds to five decimal places.

You can change how latitudes and longitudes are displayed by choosing File > Settings.

The GTransData folder contains files connected to Gtrans, e.g. databases containing the transformations that are included in the program, examples of coordinate files and plugins for export and import of files.

You can locate the folder by choosing Application > Open Explorer.

Yes. This can be done by writing a plugin in the programming language Lua. You can see how the built-in plugins for k- and csv-files are constructed in the ..\GTransData\Plugins\Coordinates folder.

There are no transformation parameters defined to/from WGS 84. The reference frame SWEREF 99 that is used in Sweden, is globally adapted and is equivalent to WGS 84 for many applications.

Read more about the relation between WGS 84 and SWEREF 99.

Delete the database files (located in ..\GTransData\Databases) and then reinstall the program. The existing version of Gtrans is then uninstalled and in connection with the new installation the databases are recovered.

Yes, contact the Geodesy department and we will send you a zipped file that you can unzip and run the software from, without having to install it on your computer.

Contents of this page may be automatically translated, we take no responsibility for the accuracy of the translation. Feel free to contact our customer support centre if you have any questions.

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