What Is an FNA File?

How to Open, Edit, and Convert FNA Files

Screenshot of several FNA files in Windows 10
FNA Files.

A file with the FNA file extension is a FASTA Format DNA and Protein Sequence Alignment file that stores DNA information that can be used by molecular biology software.

FNA files, specifically, may be used to hold just nucleic acid information while other FASTA formats contain other DNA-related information, such as those with the FASTA, FAS, FA, FFN, FAA, FRN, MPFA, SEQ, NET, or AA file extensions.

These text-based FASTA formats originally arose out of a software package with the same name, but are now used as a standard in DNA and protein sequence alignment applications.

Note: FNA also refers to some technology terms that have nothing to do with this file format, like ​final network acceptance, file name/attribute augmentation facility, Fujitsu network architecture, and fast neighbor advertisement.

How to Open an FNA File

FNA files can be opened on the Windows, Mac, and Linux operating systems with Geneious. To do this, navigate to the File > Import menu and choose to import the FNA file via the From File... menu item.

Note: Geneious is not free but you can request a 14-day trial to try it out.

You might also be able to open FNA files with BLAST Ring Image Generator (BRIG).

Tip: Try opening your FNA file with Notepad++ or another text editor if the program ideas above aren't working out.

The file might indeed be text-based and simple to read, or you might find that your specific FNA file has nothing to do with the FASTA format, in which case opening the file as a text document may reveal text that identifies what was used to create the file or what format the file is in.

If you find that an application on your PC does try to open the FNA file but it's the wrong application or if you would rather have another installed program open FNA files, see my How to Change the Default Program for a Specific File Extension guide for making that change in Windows.

How to Convert an FNA File

I can't verify this since I haven't tried it myself, but you should be able to use Geneious to convert an FNA file to lots of other formats, like FASTA, GB, GENEIOUS, MEG, ACE, CSV, NEX, PHY, SAM, TSV, and VCF. This can be done through Geneious' File > Export menu.

Geneious should also be able to convert the FNA file to an image file in the PNG, JPG, EPS, or PDF format via the File > Save As Image File... option.

Although you can't normally just rename a file's extension to something else and expect it to work in the same manner, you can rename an .FNA file to an .FA file if your particular DNA sequencing software will only recognize the FA format.

Note: Instead of renaming file extensions, you'll want to use a free file converter to convert other file types. In the case with FNA and FA files, it just so happens that some programs will only open files that have the FA file extension, in which case renaming it should work fine.

Is Your File Still Not Opening?

If after using the programs from above, you still can't get your file to open, you might find that the file extension doesn't actually read .FNA but instead something that just looks similar.

For example, FNG (Font Navigator Group) files look an awful lot like they say ".FNA" but if you look closely, only the first two letters are the same.

Since the file extensions are different, it's an indication that they're of a different file format and will most likely not work with the same programs.

The same could be said for many other file extensions like FAX, FAS (Compiled Fast-Load AutoLISP), FAT, FNTA (Aleph One Font), FNC (Vue Functions), FND (Windows Saved Search), and others.

The idea here is to just make sure the file extension reads .FNA. If it does, try again to use the programs from above to open or convert the FNA file. If you have a different kind of file, research the file extension to find out which applications are needed to open or convert your particular file.