What are FLAC Files & Are They Worth Using?

FLAC is an open-source audio “format” able to store lossless compressed audio. It offers CD (or higher) quality music playback and is almost as widespread as MP3 or AAC.

• But is FLAC the highest-quality format you can get, or is there a better one?
• Does it make sense to listen to FLAC files over AAC/MP3?

We answer all the questions in the article below.

What are FLAC Files

• The appeal of using FLAC files is that they retain all the original audio data while compressing it to save disk space. And it’s free to use.

FLAC, or “free lossless audio codec”, is technically a compression codec or “audio coding format”, a set of instructions on how to compress and store a PCM (uncompressed and unprocessed) file in lossless quality (it retains all the original data).

Furthermore, FLAC’s most significant appeal is that it’s open-source and has royalty-free licensing, making it widely compatible across all platforms and free to use by anyone.

Another major convenience of FLAC is its support for metadata (or audio information), which the end user can also rewrite (metadata lets you store info about the artist, song title, music genre, and even lyrics and album art).

How does FLAC compress audio files?

As mentioned, FLAC compresses the audio data, lowering the file size to 50% of its original size.

FLAC uses compression similar to zipping, which combines repetitive data and only remembers its position. It also uses predictive algorithms and corrections.

• The predictive algorithm looks at the samples’ pattern and predicts the position of the following sample. That way, it doesn’t need to save the location of every single sample.
• However, predictions aren’t always accurate, so they are combined with corrections so that predictions are accurately placed during the decoding process.

It sounds like a lot of extra work, but it takes less data. Bits that are impossible to predict by the algorithm are left intact.

What is important to know is that all this compression is later decompressed during decoding, so what you’re listening to using (wired) headphones is uncompressed audio data.

How effective is FLAC compression?

FLAC offers 9 levels of compression, each reducing the final file size by a few extra megabytes. It ranges from 0 to 8, with the latter taking the least disk space.

However, it also takes the longest to encode and requires more processing power to decode, which can affect energy consumption.

We used a 27.869-kilobyte (kB) WAV file and converted it into FLAC. Here’s how file size changes based on FLAC compression level:

From FLAC 0 (least compressed) to FLAC 8 (most compressed), the file size shrunk by 7.3% or 1.38 megabytes (MB).

Are FLAC files the highest sound quality?

FLAC files aren’t the highest sound quality possible, even if they’re made from the original master file, although the reason is somewhat silly. But first:

• Having a FLAC file doesn’t automatically mean the music will sound the same as an original (studio) master file. FLAC file is only as good as the source, so if your FLAC files originate from ripping a CD, the latter doesn’t represent original master quality (what is remaster vs. original).
• Some diehard audiophiles will argue that any compressed audio files put a strain on electronics, which can introduce unwanted noise. While that’s only measurable with equipment and not audible with human ears, it’s still something you must consider when discussing audio quality.

Difference Between FLAC and Other Audio Formats

• FLAC can store studio-quality audio, making them one of the best ways to store audio, but it isn’t the best due to compression, albeit lossless.

FLAC files are just one way of storing your music, as there are numerous other lossy and lossless audio formats. Here’s how they compare to each other.

Here’s a quick overview of the differences between different audio formats/sources:

Down below, we’ll go into more detail for each format.

FLAC vs. MP3

MP3, or “MPEG-1 Audio Layer-3”, is one of the most well-known compressed audio formats worldwide. It’s known to be space efficient, which is why it’s still widely used today. However, it’s also among the worst for sound quality.

• Sound quality: (Max quality – 16-bit/44.1kHz with 320kbps bitrate) MP3 is worse than FLAC since it’s a lossy audio format. It takes away redundant data that most people can’t hear. By redundant data, we mean frequencies above 16kHz and those that are next to a louder frequency (you can’t hear a quiet frequency next to a loud one due to auditory masking, which makes it redundant). With high-end audio equipment, you can hear the difference between MP3 and FLAC primarily in higher frequencies, which are slightly more resolving. 
• Compression: Heavy compression is combined with removed redundant data to ensure small-size files.
• File size: MP3 files can be up to 90% smaller than original uncompressed lossless ones.
• Compatibility: MP3 is widely compatible with all audio devices, even old ones. It also has excellent metadata support.

FLAC vs. WAV

WAV, or “Waveform Audio File Format”, is another well-known audio format typically used for audio CDs. Its quality makes it appealing, but it takes up a lot of disk space.

• Sound quality: (Max quality – 32-bit/192kHz with higher than 12.000kbps bitrate) WAV is technically better than FLAC since it’s an uncompressed and lossless format, so in no processing stage, it messes with the audio data. That said, it’s implausible to hear any difference between the two formats, even if you own crazy expensive equipment.
• Compression: WAV is an uncompressed audio format.
• File size: Since it’s uncompressed and raw audio data, file sizes can be huge, up to 50% larger than already big FLAC files.
• Compatibility: You can play WAV files almost anywhere, even on Apple devices. However, you might encounter incompatibility issues with some radios or car stereos. Also, WAV has poor metadata support.

FLAC vs. CD-quality

CD quality refers to uncompressed WAV audio format stored at 16-bit/44.1kHz.

• Sound quality: (Max quality: 16-bit/44.1kHz with 1.411kbps bit rate) In most cases, FLAC is mentioned in the same sentence as CD-quality, even though FLAC can store higher-quality PCM audio data than CD. So, FLAC can be better than CD quality.
• Compression: Audio data on a CD is uncompressed.
• File size: Like with WAV, CD-quality files are up to 50% larger than FLAC.
• Compatibility: You can play audio CDs with any CD player at home or in a car, but you can only play it on the go if you have a portable CD player). Also, CDs have good metadata support but can’t save album art or lyrics.

FLAC vs. streaming

Most listeners have jumped to streaming music instead of local storage due to convenience and access to millions of songs at the tip of the finger. However, streaming has some hidden traps.

• Sound quality: (Max quality: 24-bit/192kHz with 4608kbps bitrate (TIDAL)) Despite the impressive numbers streaming services advertise for their high-res audio tiers, local FLAC files are still a higher-quality option for diehard audiophiles. Most importantly, streaming sites tend to subdue the dynamic range to save that little extra storage on their servers. Also, TIDAL’s MQA is a compressed lossy format. A really good one, but still lossy.
• Compression: To save storage on servers, which need to hold tens of millions of songs, streaming platforms heavily rely on compression.
• File size: Depends on the plan you’re using, but it can vary from less than 90% of its original size to around 50% (when songs are stored in FLAC).
• Compatibility: As long as your device supports the streaming app or internet browser, you can stream music wherever you want.

Advantages of Using FLAC Files

• FLAC can store high-resolution audio, its files are half the size of uncompressed alternatives, and it is widely supported by many everyday audio playback devices.

If you’re still among users who prefer storing music locally (like we do) and want the best audio quality possible (that’s available to consumers), here’s why you should use FLAC above other audio formats.

Sound quality

The most obvious advantage of using FLAC is preserving the original source audio. Even if your FLAC music derives from CDs, you can still expect better resolution and dynamics compared to MP3, AAC, or M4A.

Of course, you will only truly appreciate FLAC quality when using higher-grade audio equipment that can actually reproduce that extra resolution.

If you’re playing music from Bluetooth speakers, car stereo, or via budget headphones, you won’t experience the benefits of using FLAC.

Some might argue that even using lossless files and Bluetooth headphones doesn’t make sense since Bluetooth codecs, even LDAC, make your audio lossy.

Storage efficiency

As mentioned above, FLAC offers various levels of compression, but in general, it can lower the original file’s size by 50%.

That’s still a lot compared to a 90% reduction in size with MP3 lossy compression. However, computer storage is affordable nowadays, so you no longer have to look for each megabyte of free space.

FLAC file size vs. MP3, WAV, AAC …

To have a clearer picture of how much space a FLAC file takes compared to other formats, we made a comparison table.

We took a WAV file and convert it into as many different audio formats as possible. Here are the results:

Compatibility and accessibility

As long as you don’t have an Apple device or older audio receiver with a USB input, you can rest assured anything can play your FLAC files, regardless of the compression level.

That includes smartphones and similar modern gadgets, radios, AV receivers, etc.

On the other hand, to get FLAC files you either buy them from websites like Bandcamp, Qobuz Store, ProStudioMasters, etc., or you use dedicated software to rip music off your original CDs (and use it for personal use).

How to Play FLAC Files?

• You can play FLAC files on pretty much any music player, with the expectation of Apple iOS devices, where achieving FLAC playback involves extra steps.

FLAC is widely used in the audio industry, so almost all audio devices support FLAC playback. Simply use a music player app of your choice. These are popular among audiophiles:

• Foobar2000
• Aimp3
• Musicolet

The only devices where FLAC playback is questionable are:

• Car stereos
• Apple devices

What about Apple devices?

Apple have added FLAC support in iOS 11, but it involves extra steps to get it to work. Native apps like iTunes or Apple Music don’t support FLAC files, so:

• You must download a music player that can, like VLC.
• Convert FLAC files to ALAC or APE.

When it comes to MacOS devices, they should support FLAC playback. Otherwise, you can use third-party music players to make that happen.

Frequently Asked Questions (FAQ)

Conclusion

Even after the entire audio industry shifted from selling individual digital songs to streaming, FLAC remains a go-to solution for hi-res audio for both audiophiles and streaming platforms.

The most significant advantage of FLAC is that it offers CD (or higher) quality music without taking up enormous space on your hard drive.

If you own a good pair of headphones, listen to some FLAC files and compare them to MP3 versions. We’re sure you’ll hear at least a slight difference.

Peter Susic

From a childhood fascination with sound, Peter’s passion has evolved into a relentless pursuit of the finest headphones. He’s an audio expert with over 5 years of experience in testing both audiophile and consumer-grade headphones. Quote: “After many years, I can confidently tell which headphones are good and which are terrible.” Find his honest opinion in his reviews.