Convert ASC to CSV
ESRI grids and TomTom POIs.

Convert ASC to CSV online for grids or POI data

An ESRI ASCII Grid stores raster data as a plain-text header followed by rows of cell values. The header describes the number of columns and rows, the lower-left grid origin, and the cell size. This free online ESRI ASCII Grid to CSV converter reads that structure and writes each cell as a record in a downloadable comma-separated file. Use the CSV in a spreadsheet, a database, a script, or another data workflow that works with tabular rows.

What the CSV contains

Every output record includes x, y, and value, plus one-based row and column fields so you can trace a record back to its position in the raster. The coordinates refer to the center of each cell. Rows in an ASCII Grid are stored from top to bottom; the converter accounts for that ordering when it calculates each y coordinate. The first data row therefore maps to the northernmost row of the grid.

Cell corners, cell centers, and native units

The format allows an origin written as xllcorner and yllcorner, or as xllcenter and yllcenter. When the header gives a corner, the center of the first cell is half a cell size east and north of that origin. When the header gives a center, that coordinate is used directly. The cell size is added for each step across or down the grid. By default, the output uses the same coordinate system and units as the input file; set an output CRS to transform coordinates.

An ASCII Grid header does not include enough information to identify its map projection. Add a matching .prj sidecar, enter the source EPSG code, or paste a WKT or PROJ definition before choosing a different output coordinate system. You can reproject to WGS 84 longitude and latitude or Web Mercator with one click, or enter another EPSG code. For EPSG definitions not built into the converter, only the code is retrieved from epsg.io; raster content remains local.

Keep or omit NoData cells

If your grid declares a NODATA_value, those cells are included in the CSV by default, preserving the complete grid. Clear the NoData option to omit them when you only need cells that contain data. If the header does not declare a NoData value, every grid value is exported. The converter also checks that the header dimensions match the values in the file and reports an error when the input is incomplete or malformed.

Private conversion in your browser

Choose a grid from your device and review its preview before downloading. The converter reads the cells and builds the CSV locally, so the grid is not uploaded to BFOTKit. If you enter an EPSG code that the browser library does not recognize, only that code is sent to epsg.io to look up its definition.

Batch convert grids and preview the raster

Select multiple .asc files at once or choose a ZIP archive containing grids. For each grid, the converter creates a separate CSV and packages batch results into one ZIP download. Include matching .prj files to provide source CRS information. Use the preview selector to inspect each raster’s cell pattern and coordinate extent. The preview is rendered locally without map tiles, so file contents and coordinates are not sent to a basemap provider.

The converter supports up to 200 MB of combined input and 1,000,000 output records per batch. Large files depend on the memory available to your browser and device. Your selected files are processed in the browser; only an EPSG code may be sent to epsg.io to retrieve an otherwise unavailable projection definition.

Convert a TomTom POI ASC file to CSV

Some navigation files also use the .asc extension. A TomTom POI ASC is a list of places rather than a raster grid: each record contains longitude, latitude, and a place name. Choose one alongside your ESRI grids or in a separate batch. The converter recognizes the coordinate records, keeps names intact, and creates a CSV with longitude, latitude, and name columns. Coordinates can be decimal degrees or the degree, minute, and second forms used by TomTom POI text files.

To identify the format before converting, inspect the start of the file. An ESRI ASCII Grid has header lines such as ncols, nrows, xllcorner, and cellsize, followed by rows of numeric cell values. A TomTom POI file has one coordinate pair and name per line, often with a quoted name. You can select several ASC files or add them to a ZIP; BFOTKit detects each file and creates a separate CSV for each dataset.

Convert an ASCII table or terminal output to CSV

Not every ASCII-to-CSV task starts with an .asc file. If you have a table copied from a README, terminal, technical document, or text report, paste it into the ASCII table section. BFOTKit detects common columns divided by pipe characters, ASCII or Unicode box borders, tabs, and repeated spaces. You can trim whitespace, skip blank lines, use the first row as column headers, and choose whether to quote every field in the CSV.

The text table converter shows a preview before you copy or download the result. Empty fields between separators are preserved, and commas or quotation marks inside a cell are escaped according to CSV rules. For example, a table such as | Item | Count | becomes two CSV columns. The tool handles structured tables rather than trying to guess columns from ordinary prose. Paste up to 5 MB of table text at a time.

Three ASC and ASCII inputs, one local workflow

The file converter detects ESRI raster headers and TomTom POI point records automatically. The text converter handles pasted ASCII tables separately, since a visual table is not the same structure as an ESRI grid or a TomTom location list. Each workflow produces a preview and a CSV that can be opened in spreadsheet software. Grid conversion includes cell geometry, POI conversion keeps names and coordinates together, and table conversion preserves its columns and optional header row.

The ASC file parser supports the two structures described above rather than arbitrary files that happen to use the .asc extension. If a POI provider reverses its coordinate columns, choose the matching order in the converter; the place name should follow the coordinate pair. Review the preview and skipped-line count before saving. For ESRI raster data, use the cell preview and coordinate reference settings to verify that the output matches your GIS workflow.