How do you turn your favorite MP3 into a ringtone for your mobile phone? What is the quickest way to convert a PowerPoint presentation into a video file? How do you convert Microsoft Office documents for reading a Kindle?

These are some common questions and what follows is a detailed guide on how you may convert files of just about any format to another format using free tools. If you are not too sure of the file format, see how to open files on unknown extensions.

Convert any type of file for Free

I have covered both web-based and software-based conversion utilities though I prefer the latter option for a couple of reasons - conversion on desktop is often faster, you get to convert your large files offline and, most importantly, you don’t have to worry about privacy issues since there’s no need to upload files to another server for conversion.

A. Video Files (including DVDs and Online Video)

If you would like to rip your DVD movies into smaller video file for, say, watching on your mobile phone or tablet, VidCoder is a good option (see detailed guide). HandBrake is also a popular tool for ripping DVDs though new users may find VidCoder a little easier to use.

Miro and Hamster are simple utilities that can help you convert between all popular video formats – like MP4, AVI, WMV, FLV, MKV, MOV, WebM, etc. – in two easy clicks. There are built-in presets for iPod, iPad, Blackberry, and other mobile devices so that makes conversion a lot more simple for newbies.

If you are looking for a more advanced video converter than can handle any weird video format and does more than just plain conversion, check out MediaCoder and SUPER – not exactly user-friendly but extremely powerful.do

In case you have the bandwidth and don’t mind converting your video files online, MovAvi and Heywatch are recommended choices. xVideo and Tooble are free utilities that can both download and convert Flash video from the web – they support all major video sharing sites including YouTube.

B. Audio Files

Audacity is absolutely the best software program for converting audio files from one format to another. If you include the FFmpeg library in your installation of Audacity, it will even let you extract audio from video files. If an audio format is not supported in Audacity, you may still convert it with media.io, an online audio conversion service.

You may use Audacity to set your favorite MP3 song as a ringtone on your mobile phone but for something more simple, try Audiko. This is an again online tool where you upload an audio file (or specify the URL of a YouTube music video), choose a fragment and save it as an MP3 ringtone. You may also make iPhone ringtones with iTunes but only for non-DRM music.

FLV.to is an online app for downloading and converting Flash video into an MP3 file. Also check out Myna, an online audio editor that you may use to convert audio files or for merging multiple formats into a single format.

C. Fonts

When you are switching between a Mac and a PC, the fonts may not be compatible across OSs. Here’s a simple online tool where you may convert your existing font into any other format.

The font conversion service supports all the common font formats – like TrueType (.ttf), OpenType (.oft) and PostScript (.ps) – as as some of the obscure formats.

D. eBooks, Help Files, etc.

Not long ago, CHM (compiled HTML) was a preferred format for distributing help files and even e-Books. The CHM format is supported on Windows only but you may use the HTML Workshop tool to decompile CHML into HTML and CSS file that you may then read in any web browser on any device.

EPUB is now a standard file format for e-books and there are quite a few good converters to deal with this format. There’s Calibre that you may use to convert all popular document format into EPUB books or even the revers - converting EPUBs into PDF, Text or HTML files. You may use consider Sigil, a WYSIWYG ebook editor that can convert HTML and text files into EPUBs.

Amazon offers a free command line utility for Windows, Mac and Linux called KindleGen that you may use to convert any HTML, XML or EPUB book into a Kindle Book (MOBI).

Get Flipsnack to convert your PDF document into a Flash-based flipping ebook.

E. Office Documents and PDFs

Use Nitro PDF Reader to convert any of the Microsoft Office file formats - like .doc, .xls or .ppt – into PDF files. The same tool may also be used for convert pages of your PDF documents into text or into image formats.

Documents written in Office 2010 specific formats – like docx or xlsx – can be converted to equivalent Office 2003 formats using the Zoho Converter.

If you wish to convert multiple Office files to PDF in a batch, just upload them all to Google Docs and export everything as PDFs. The Google Docs viewer may be used for converting any of the online documents into PDF.

PowerPoint 2010 has a built-in Save as Video feature but if you on a different version, read this detailed tutorial for converting your slideshow into a self-playing movie.

F. Images, Icons and Animated GIFs

All image gallery tools – including Picasa and Windows Live Photo Gallery – can help you convert images from one format to another. Use FFmpeg if you wish to convert videos into Animated GIFs.

You can convert your pictures to ASCII art either using degraeve’s online tool or with the help of AscGen, if you want to do the conversion offline.

Get hold of Windows Live Movie Maker or Microsoft Photostory to convert your images into a video that you may later upload to YouTube.

iConvert is a useful online app that will convert any image or icon into Windows and Mac icons in one step. It will also create an .ico icon file from that image for your website. You may also use favicon.cc to convert and tweak your images into favicons.

There are several OCR tools available for converting a scanned image or digital photograph into digital (editable) text with Google Docs emerging at the top.

G. Web Pages, Blogs and Wikis

You can convert web pages into images using Bounce (online) or, if you want to automate the capture, use SiteShoter. Convert a web page into a PDF document for archiving with PDFmyURL or Web2PDF.

You may convert a blog, or any site that offers a RSS feed, into a PDF newspaper with FiveFilters. There’s also Tabbloid from HP that lets you convert one or more feeds into a PDF magazine for offline reading.

The BookGlutton Converter may be used for converting web pages into EPUB format though you’ll tweak the HTML a bit before submitting it for conversion. There’s another service called 2epub for convert HTML files to EPUB or MOBI that you may transfer to your Sony Reader, Nook, Kobo or Kindle.

H. Everything else..

Wiki users may use the htmltowiki tool to convert HTML markup into MediaWiki format. There’s Pandoc for convert files between various markup formats including LaTeX, DocBook, MediaWiki and EPUB. Also see related guides for merging address books and your email accounts. Use Tweetbook to convert your Tweets into a PDF book.

Finally, such a list would be incomplete without the mention of all-in-one conversion services like Zamzar, Convert.Files and YouConvert that seem to handle nearly every file format from music to images to ebooks. These services are like one-stop shops but the downside is that the conversion is not instant and you have to provide your email address for them to send the converted files.

Related reading: How to Embed almost anything in your Website