All about BCL Files

The BCL file type is primarily associated with FASTQ.

BCL	File extension: BCL
	File type:	base call data file

What is a BCL file?

BCL files mostly belong to FASTQ by Illumina. BCL files are created and used by DNA sequencing instruments, HiSeq and MiSeq that are developed by Illumina.

• Main Features: Primary Analysis of a DNA sample is performed using Illumina sequencing instruments to gauge the channels' intensity in encoding various bases and subsequently establish the base (this is called a base call) with the highest likelihood (called Q score) at a particular position in the sample sequence. During each such sequencing cycle, the Real-Time Analysis (RTA) software from Illumina machine creates a BCL file containing the information of these base calls and associated quality values (Q scores). The data in these BCL files is stored in a binary format and is representative of the raw data output during each run sequence. The process that generates BCL files is very efficient since each base calling is separately recorded by the machine before proceeding further.
• Adoption: Software such as Casava,bcl2fastq, Eland and iSAAC aligner are used for further analysis of these raw BCL files by converting them into a structured form and saved with FASTQ file extension. FASTQ format is a text-based sequence format that saves the raw-sequence information and quality scores.

How to open BCL files

You need a suitable software like FASTQ to open a BCL file. Without proper software you will receive a Windows message "How do you want to open this file?" or "Windows cannot open this file" or a similar Mac/iPhone/Android alert. If you cannot open your BCL file correctly, try to right-click or long-press the file. Then click "Open with" and choose an application. You can also display a BCL file directly in the browser:. Just drag the file onto this browser window and drop it.

Online BCL Text Viewer

Choose your .bcl file to analyze

or drag and drop it here

Online File Viewer

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BCL file format:

The file format, which is the arrangement and type of data in a file, determines which program can open the file. Often, the file format can be deduced from the file extension or the initial bytes (called the signature). Frequently, however, one file extension is used by different programs for different file formats, and one file format for different file extensions. So you need a detailed analysis of a file to find out the format and the associated program. Our evaluation of the BCL files looks like this:

The BCL file extension is not found very often and includes various formats for various programs. The file formats most commonly found in BCL files are:

• 35% of all BCL files store the data in the UTF-8 file format. UTF-8 is the World Wide Web's most common character encoding for Unicode. UTF-8 files can be viewed with any text editor. These files start with the 3 bytes  (hex: EF BB BF), the so called byte order mark (BOM). These files are text files, so they contain words and text. The average file size is 78 bytes with most files being between 52 bytes and 180 bytes in size. The file type is relatively new. The files contain the following words: Users and Desktop. A usual file name is ConversionList1.bcl.
• 5% of all BCL files use the popular config file format. A configuration file is used by computer software to store settings. It consists of a text-based content with a structure and syntax comprising key–value pairs for properties, and sections that organize the properties. These files are text files and can therefore be read using a text editor. The files are often between 420 bytes and 500 bytes in size. Certain words are almost always found in the files, such as [Log], hash and imei.

The remaining 60% of all BCL files are different files with different signatures, such as GZIP, XML, laD and Sub. Sometimes used for commandlist, export, mclog, subn, lists or sets. You can get all the details of your BCL file by dragging it onto this page or by clicking the button "Choose your .bcl file to analyze" above.