View DEM files in your browser
The text files the USGS kept the heights of its maps’ quads in. Open one right here, shaded in its place over OpenStreetMap. The file never leaves your device.
Or drop it anywhere on this page
What you'll see
Your heights open in their place on the map, colored from low to high and shaded with light from the northwest.
- Colored from low to high • Shaded from the northwest
- Inspect • The height under the cursor
- Measure • A profile of the heights along a line
- Export • The view as PNG, the profile as CSV
About DEM
The US Geological Survey kept the heights of its 7.5 minute quads, 30 or 10 m apart, and of each degree, 3 arc seconds apart, in DEM files until the National Elevation Dataset took over in the 2000s. Canada’s CDED, made the same way, and a lot of old GIS data still come as .dem.
A DEM is text in records of 1024 characters: an A record with the quad’s name, corners, system and units, then a B record for each profile, a column of heights from south to north, and sometimes a C record of its accuracy. Most are in UTM with heights in meters or feet, and the ones of a degree in arc seconds.
Filepeek reads the records, places the quad through its UTM zone and datum, and colors the heights from low to high, shaded with light from the northwest. Inspect gives the height under the cursor, Measure draws a profile along a line, and Export saves the view as PNG and the profile as CSV.
USGS Digital Elevation Model
.dem
Format
- MIME type
- text/plain
- Made by
- The US Geological Survey
Inside the file
- Holds
- Heights in profiles
- Records
- A, B and C, in text
- Systems
- UTM or arc seconds
- Units
- Meters or feet
Opens in every browser
Filepeek opens USGS DEMs on a map in Chrome, Edge, Firefox and Safari. On their own, browsers download them or show their text.
- YouChromeOpens through Filepeek
- YouEdgeOpens through Filepeek
- YouFirefoxOpens through Filepeek
- YouSafariOpens through Filepeek
Apps that open DEM
- WindowsQGIS • Global Mapper
- MacQGIS • Global Mapper
- iPhone and iPadNo app built in opens it
- AndroidNo app built in opens it
Questions
How do I open a DEM file?
Drop it on this page or choose Peek a DEM. The quad opens in its place on the map.
Is every .dem file a map of heights?
No. Counter-Strike, Team Fortress 2 and other Source games save their match recordings as .dem demos too. Filepeek tells them apart by what’s inside and puts only the heights on the map.
Does it open DEMs in GeoTIFF?
Yes. Heights in a GeoTIFF open on the map the same way, through the GeoTIFF reader, and so do SRTM’s HGT tiles and DTED.