What is a .ASC file?
ASC is an Esri ASCII grid - a plain-text raster of elevation or other gridded values.
- Did you know
- The ASCII grid stores a whole raster as readable numbers, easy to inspect by eye.
- The Esri ASCII grid begins with a short header - ncols, nrows, corner coordinates, cellsize and an optional NODATA_value - followed by the cell values.
- It is also known as the Arc/Info ASCII grid, and its NODATA_value defaults to -9999 where none is given.
- What Analyser reads
- Inspect geospatial and GIS files without a map: TopoJSON, OpenStreetMap XML, Esri Shapefile siblings (SHP/SHX/DBF/PRJ/CPG), world files, GML, NMEA GPS logs, IGC flight logs, MapInfo TAB/MIF, GDAL VRT, PMTiles, DTED terrain, Esri ASCII grids and SRTM .hgt - surfacing CRS/EPSG, feature/record counts, bounding boxes and elevation ranges. GRIB/NetCDF/GeoPackage/MBTiles/MrSID/ECW identified.
- Depth of analysis
- .ASC is an identification-grade format: Analyser recognises it from its bytes and decodes the header metadata it carries, rather than opening it in a full viewer. Formats that do get a full viewer are marked "Full" on the formats page.
- Open a .ASC file
- Drag a .ASC file onto the Analyser home page (or tap to pick one). It is identified entirely in your browser - nothing is uploaded, there is no account, and it works offline once installed.