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LAS (Log ASCII Standard)

This LAS information site provides links to the File Specifications of the various versions of LAS, plus links to LAS Software. LAS versions 1.2 and 2.0 were written and maintained by the CWLS as public domain well log data formats. LAS version 3.0 was written and is maintained in the public domain by the LAS 3 Committee. You are free to use and distribute these data format Specifications and related Software provided you recognize that the ownership of LAS 1.2 and LAS 2.0 Specifications and Software belong to CWLS, and ownership of LAS 3.0 Specifications and Software belong to the LAS 3 Committee.

The following links are presented in two groups: LAS Specifications & Examples, and LAS Software. Select a link from the first group to download the file format Specifications and examples for the corresponding version of LAS. Use the second group of links if you want to download LAS software.

The LAS version 2.0 link in the first group will initiate the download of an Adobe Acrobat ‘pdf’ file containing the LAS version 2.0 Specifications updated in Jan 2014. The documentation includes a number of LAS 2.0 examples.

The LAS Applications Software was designed to perform routine operations on LAS 2.0 files such as correcting LAS files for common errors, conversion from version 1.2 and 3.0, re-sampling, wrapping, un-wrapping, depth conversion, converting text to LAS 2.0, a Certify routine, merging, changing curve mnemonics etc. It was designed for processing large volumes of LAS 2.0 files. The application uses Microsoft “.NET” software and is compatible with Windows XP, Vista and Windows 7, Windows 8.

The LAS Certify Software is the only LAS version 3.0 targeted software available here. This MS Windows compatible application handles LAS version 3.0 and earlier data files. The LAS 3 Committee chose to not create an LAS 3.0 version of reformat, preferring to leave that for commercial software developers.

LAS File Specifications & Examples

Txt IconLAS 1.2 Specifications September 1990 (Text File) – historical, no longer supported

Txt IconLAS 2.0 Specifications January 2014 (Adobe Acrobat File) – 2.0 examples contained in the PDF file

PDF IconLAS 3.0 Specifications June 2000 (Adobe Acrobat File) – Zip Icon3.0 example LAS file (ZIP File)

LAS Software (Windows based)

Txt IconLAS Applications Software (LasApps) October 2015 – includes certification process which handles all LAS version data files. View LasApps Software Operating Instructions

Zip IconLAS Certify Software (lascertify) November 2000 – certification only program which handles all LAS version data files

Other LAS Software

Other LAS software (both free and commercial) can be found by searching for “Log ASCII Standard” and variations thereof. Software development libraries have been written in languages such as Ruby and Python.


If you have any questions please contact:

For LAS 1.2, 2.0 items: Case Struyk, P.Eng. –

For LAS 3.0 items: Ken Heslop, P.Eng. –