Bit Depth vs. Bit Rate in Audio Recording

One measures speed; both indicate quality

By
Mark Harris
Mark Harris
Writer
  • University of Wolverhampton
Mark Harris is a former writer for Lifewire who wrote about the digital music scene and streaming music services in an easy to understand, no-nonsense manner.
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Updated on October 21, 2021

The digital audio terms bit depth and bit rate are so similar that many people assume these terms mean the same thing. It's easy to confuse the two, but these are different concepts. We compared bit depth and bit rate to help reduce some of the confusion.

Bit Depth vs Bit Rate
 Lifewire

Overall Comparison

Bit Depth

  • Determines audio fidelity.

  • Controls how much data is in audio files.

  • Impacts clarity and detail.

Bit Rate

  • Measure of bandwidth in audio files.

  • Impacts playback quality.

  • Factor in determining file size.

You might need to know about bit rate when choosing the best audio format for your portable device or when converting to the MP3 format with an audio converter tool or another program such as iTunes.

Bit depth becomes important when digitizing your analog music collection or needing the highest possible sound quality.

Bit Rate Pros and Cons

Advantages

  • Sets the overall number of bits of data, determining quality.

  • Control the size of your files.

  • A measure of bandwidth, meaning you'll need a connection to support it.

Disadvantages

  • Doesn't detail to a lower quality recording or rip.

  • Can't determine how much data is in the file.

Bit rate is a measurement expressed in kilobits per second (Kbps), which is thousands of bits per second. Kbps is a measure of the bandwidth of data transmission equipment. It shows the amount of data that flows at a given time across a network. For example, a recording with a 320 Kbps bit rate is processed at 320,000 bits per second.

You can also express bit rate per second in other units of measurement, like megabits per second (Mbps) and gigabits per second (Gbps). These are only used when the bits per second meet or exceed 1,000 Kbps or 1,000 Mbps.

A high bit rate recording delivers better quality audio and takes up more space on a computer or mobile device. However, you aren't likely to notice the improved quality over one of lower quality unless you have high-quality headphones or speakers. For example, if you're listening over a standard pair of earbuds, you probably won't notice the difference between a 128 Kbps file and a 320 Kbps file.

Bit Depth Pros and Cons

Advantages

  • Controls how accurate a recording is.

  • Determines the level of detail in the recording.

  • Dictates how much data describes the audio.

Disadvantages

  • Doesn't add detail to a file that wasn't already there.

  • Can't control the amount of bandwidth needed to play a file.

At first, bit depth might seem a complicated subject. In its simplest form, it measures how precisely a sound is represented in digital audio. The higher the bit depth, the more accurate the digital sound.

You probably encountered songs that come at a particular bit rate from MP3 download services or streaming music sites, but little is said about bit depth. However, if you plan to digitize your collection of vinyl records or analog tapes to store them as high-quality digital audio files, you need to know about bit depth.

A higher bit depth gives a more detailed sound recording. A low bit depth causes quiet sounds to be lost.

The measurement for bit depth is bits. For each 1-bit increase, the accuracy of the recording doubles. The higher the bit depth, the better the recording sounds.

Audio CDs use 16 bits per sample, while Blu-ray discs and DVDs use 24 bits for each sample. The sound quality achievable on the Blu-ray disc or DVD is higher than can be achieved on an audio CD.

This attribute influences how much detail you can capture from the original recordings. Getting the bit depth right is also critical for keeping background signal interference at a minimum and affecting the volume of recordings.

Final Verdict

Generally, the bit rate is a relevant concern when working with audio. Why? You have little choice with CDs. CDs are at 16 bits per sample. Keeping the bit rate high will matter more.

Blu-ray audio is gaining traction. It allows for greater bit depth and, ultimately, more detailed audio. You won't find every artist releasing on Blu-ray just yet, so it's a special case type of situation.

The most practical thing you can do to ensure your digital audio is the highest quality is to use lossless formats like FLAC and WAV.

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