Free online TXT to ASC converter

A device, database, GIS program, or specialist application may require a plain-text file with the .asc extension for import or exchange. If the required ASC format uses the same text structure as the source, conversion may only require renaming the file; otherwise, encoding, delimiters, headers, or a defined export process are also needed.

What the TXT format is

.txt is a generic plain-text format. It stores characters without fonts, page layout, images, or embedded document features. Notepad, TextEdit, Notepad++, Visual Studio Code, command-line tools, database exports, scientific software, and operating systems commonly create TXT files.

A TXT file may contain prose, source code, logs, comma-separated or tab-separated data, fixed-width records, or numerical tables. The extension does not specify the character encoding, delimiter, column layout, line-ending convention, header, or data schema. Common encodings include UTF-8, UTF-16, Windows-1252, and other legacy code pages; common line endings are Windows CRLF and Unix LF.

What the ASC format is

In the text-file context, .asc commonly identifies ASCII or another application-specific plain-text file. It has no single universal structure. A receiving program may require one value per line, comma or tab delimiters, spaces, fixed-width columns, a header, a particular decimal format, or strict 7-bit ASCII.

Plain-text ASC files are readable in text editors, easy to compare, and portable between systems that support the required encoding. Strict ASCII contains only characters from the 7-bit ASCII set, so it cannot directly represent accented letters, non-Latin scripts, or many symbols. The .asc extension alone does not prove that a file uses strict ASCII.

Some other text-based formats also use .asc. An ESRI ASCII Grid contains a defined raster header followed by rows of cell values. An ASCII-armored OpenPGP file contains encoded cryptographic data with markers such as -----BEGIN PGP MESSAGE-----. These files need their own generating or exporting software; changing a TXT extension cannot create either syntax.

How to convert an ordinary TXT file

1. Keep a copy of the original .txt file.
2. Open the file in Notepad++, Visual Studio Code, TextEdit in plain-text mode, or another editor that shows the current encoding. Check that characters, columns, and line breaks display correctly.
3. Check the destination program's ASC specification. Record the required encoding, line endings, delimiter, column order, header, numeric format, and whether the file must contain only 7-bit ASCII.
4. Use File → Save As and enter a name ending in .asc. Select the required encoding. Use UTF-8 when the destination supports it; select ASCII or a specified legacy encoding only when the destination requires it.
5. On Windows Notepad, choose All files (*.*) in the file-type field so the program does not create data.asc.txt. In Visual Studio Code, use File → Save with Encoding if the encoding must change. In TextEdit, use Format → Make Plain Text before saving.
6. Reopen the saved file and inspect the beginning, end, delimiters, special characters, and line endings. Import it into the destination application and check representative records.

If the TXT already has the required content, encoding, and line endings, renaming or copying it is sufficient. On Windows Command Prompt, use:

copy input.txt output.asc

In PowerShell, use:

Copy-Item input.txt output.asc

On macOS or Linux, use:

cp input.txt output.asc

These commands copy the bytes without changing encoding, delimiters, line endings, or structure. A direct rename, such as ren input.txt output.asc on Windows or mv input.txt output.asc on macOS and Linux, changes only the filename.

Changing the encoding

If the destination requires strict ASCII and the source is UTF-8, an editor can save an ASCII copy, but characters outside the ASCII range may be rejected, removed, or replaced. With GNU iconv, a transliterating conversion can be written as:

iconv -f UTF-8 -t ASCII//TRANSLIT input.txt > output.asc

Review the output because transliteration may alter accents, symbols, and non-Latin characters, and its results depend on the installed conversion rules. Do not use transliteration when exact data preservation is required; use the encoding specified by the receiving program instead.

Using the built-in converter

You can convert the file on 101convert.com for free without installing software. Upload the TXT file, select ASC as the output format, start the conversion, and download the result. Inspect the downloaded filename and content, then verify its encoding and structure before importing it. Do not upload private keys, credentials, personal data, or confidential records unless the service's handling policy permits it.

When renaming is not enough

If the target expects an ESRI ASCII Grid, export the raster from GIS software such as QGIS or GDAL rather than renaming a text table. A valid grid normally includes fields such as ncols, nrows, xllcorner or xllcenter, yllcorner or yllcenter, and cellsize, followed by rows of cell values; NODATA_value is commonly included.

If the target expects ASCII-armored OpenPGP, create the file with GnuPG or the application that performs the signing, encryption, or key export. A normal text file renamed to .asc is not a valid PGP message or key.

Validate the result in the receiving program instead of relying on the extension. A file can have the correct name and still fail because of a byte-order mark, unsupported encoding, incorrect CRLF or LF line endings, tabs instead of spaces, missing headers, wrong delimiters, altered decimal separators, or lost characters.