What is an HGT File?

How to Open, Edit, & Convert HGT Files

Screenshot of an HGT file opened in VTBuilder
An HGT File in VTBuilder.

A file with the HGT file extension is a Shuttle Radar Topography Mission (SRTM) Data file.

HGT files contain digital elevation models, which are 3D pictures of a surface - usually a planet, obtained during the Shuttle Radar Topography Mission (SRTM) by NASA and the National Geospatial-Intelligence Agency (NGA).

Used here, "HGT" is just an abbreviation for "height." The .HGT file is normally named with the longitude and latitude that the image pertains to, within one degree.

For example, the file N33W177.hgt would indicate that it includes data for latitudes 33 to 34 North and longitudes 177 to 178 West.

Note: SRTM Data files have nothing to do with SRT files.

How To Open an HGT File

HGT files can be opened with VTBuilder, ArcGIS for Desktop, and Safe Software's FME Desktop. DG Terrain Viewer works too, for both Windows and Linux. You can also import an HGT file into Blender with the Import SRTM plugin.

Note: If you're using VTBuilder to open your HGT file, it's not done within the regular Open Project menu item. Instead, you must import the file into the program through the Layer > Import Data > Elevation menu.

See the Shuttle Radar Topography Mission home page, hosted by the NASA Jet Propulsion Laboratory, for all the basics on SRTM data, which comes in HGT format. The data itself can be downloaded from the SRTM page hosted by the US Geological Survey.

I also found a great overview of SRTM and the data produced here.

The USGS website also has some more information here, in a PDF.

Tip: If you have an HGT file that you know isn't an SRTM Data file, or it doesn't work with any of the aforementioned software, it could be that your specific HGT file is actually in an entirely different format. If so, use Notepad++ to open the file.

Sometimes there's identifiable text within the file that can help you understand what program was used to build the file, which should direct you to more information on the format.

If you find that a program on your computer does try to open the HGT file, but it's the wrong application or if you would rather have another installed program open these files, see my How To Change the Default Program for a Specific File Extension tutorial for help changing those settings.

How To Convert an HGT File

I know that VTBuilder can export an HGT file to a Binary Terrain file (a .BT file). To do this, first import the HGT file (Layer > Import Data > Elevation) and then save it using the Layer > Save Layer As... option.

VTBuilder also supports exporting to PNG, TIFF, and a number of other common, and not so common, image and data formats.

In ArcGIS for Desktop, with the HGT file already open in the program, you should be able to go to Export > Raster to Different Format to save the HGT file under a new format.

The other programs above can probably convert HGT files too. This is normally done through an Export option or a Save As menu.

Having Issues With an HGT File?

See Get More Help for information about contacting me on social networks or via email, posting on tech support forums, and more.

Let me know what kinds of problems you're having with opening or using the HGT file, and what programs you've tried already, and then I'll see what I can do to help.