What is Bit Depth

16 bit, 24 bit, 32 bit. What’s the difference, the the heck is bit depth, and which should you use when recording or bouncing your music? Let’s cover everything to know about bit depth now. This is going to get a little mathy, but I’ll keep it as simple and practical as possible.

Bit depth is a representation of the amount of dynamic range in digital audio, the maximum difference possible between the loudest and quietest possible points.

Sound goes through quite a journey of transformation from the our initial recording to final playback on someone’s speakers out in the world.

We use recording hardware to capture analog sound and convert it into a digital signal to be processed in our digital audio workstation. This hardware captures thousands of samples of this analog signal every second and is labeled with values to represent their amplitudes. The more values available per sample, the greater the dynamic range in digital audio.

Bit depth determines the number of values available it can assign to the amplitude of an analog signal.

The exact number of possible values available is determined through a simple equation: “2 to the power of (bit depth)”.

As such, 8 bit depth is 2 to the 8th power, which yields 256 values.

16 bit depth is 2 to the 16th power, yielding 65536 values.

Because we’re dealing in exponents, a higher bit depth provides an exponentially (see what I did there) larger range of values.

So 24 bit depth, or 2 to the 24th power, yields a staggering 16777216 possible values!

What is Floating Point

You may have heard 32 bit depth used with the phrase “floating point”.

Floating point just refers to how the values are labeled when we get to such staggering values. Scientific notation is used in place of fixed values.

So instead of 4294967296 (which is the number of values available for 32 bit depth represented as a fixed value), we label it as 4.294967296 × 10⁹.

The only thing to really know about floating point is that it’s a silly high number.

Higher Bit Depth=Higher Dynamic Range

Okay, so higher bit depth means more values to assign to amplitudes of our signal. Why does it matter?

Higher bit depth means a greater dynamic range (in volume) possible BECAUSE it has a greater range of values available to assign to the amplitude of the analog signal.

In other words 32 bit depth has a much greater dynamic range possible than 16 bit depth because it can more accurately catalog every amplitude in our recorded signal.

Conversely, recording at a lower bit depth increases the likelihood the analog to digital conversion will need to round to the closest value when it doesn’t have access to the proper value.

This act of rounding, essentially trying to fit a square peg into a triangle hole, is called a quantization error which introduces quantization noise into the signal.

We hear quantization noise as low white noise, also known as the noise floor.

Drop a dithering plugin (or a plugin with dithering capabilities) like Izotope’s Ozone Maximizer and set the dithering to 8 bit to hear what your mix sounds like at such a low bit depth as the dynamic range and breadth of values is greatly reduced. Immediately you’ll hear the the quantization noise of rounding values given the extremely limited range of 8 bit depth.

Incidentally dithering is the process of adding low level noise to mitigate the noise associated with reducing audio to a lower bit depth. This is typically done when converting an audio file recorded at 24 bit to the CD standard of 16 bit, but that’s a topic for another day.

Getting back to what higher bit depth means more dynamic range, remember that 8 bit has 256 values it can assign to amplitudes.

So if the signal calls for a 188 1/2 (as an example), working in 8 bit that signal would get rounded to 188 or 189, causing a quantization error/noise.

Dynamic range is the difference between the noise floor and the point of clipping.

If we’re working at 16 bit, again we have 65536 values. So that signal which had to be rounded at 8 bit will be properly represented at 16 bit, meaning no noise.

The main takeaway is that the higher the bit depth, the lower the noise floor.

How Much Dynamic Range Does Each Bit Depth Have

Here the math gets a lot easier.

Each “bit” is the equivalent of 6dB.

Therefore:

8 bit – 48dB

16 bit – 96dB

24 bit – 144dB

32 bit… well it’s A LOT higher because of the nature of the floating point. It’s basically quite a bit larger than the loudest measurable sounds on Earth so… yeah.

Too much science and math… just want to make better mixes… head hurts…

What Bit Depth Should I Use

Let’s get back to practicality here: what bit depth should you record and mix at?

When it comes to music, 24 bit is going to work just fine. Actually when it comes to any kind of audio producing in general, 99% of the time 24 bit depth is going to work just fine.

Again, 24 bit depth yields 144dB of dynamic range which is actually more than humans can hear between the quietest signal and pain/causing damage.

For more context, a musical performance in a concert hall typically has 80dB of dynamic range.

24 bit also provides more dynamic range than any microphone you’ll purchase can reproduce.

As such, 32 bit depth is largely objectively redundant in most music production. It covers values and range we have no practical use for, creating larger file sizes and taxing our system’s CPU unnecessarily.

What bit depth should you use?

Virtually everyone reading this should record and mix at 24 bit depth. If you’re mastering for a CD or a streaming service recommends 16 bit, dither down to 16 bit in the mastering stage in order to comply with the 16 bit limitations of those mediums, otherwise keep it in 24 bit.

Now let’s get back to the important stuff, like making music!

Bit Depth – TL/DR

Bit depth dictates the amount of dynamic range between the noise floor and point of clipping.
When audio is recorded or processed, its amplitudes are assigned values.
Higher bit depths have more values to assign.
If the appropriate value isn’t available (as is the case at extremely low bit depths like 8 bit), this causes quantization errors which manifests as white noise.
This white noise is known as the noise floor (again, dynamic range is the difference (in dB) between the noise floor and clipping).
24 bit depth provides 144dB of dynamic range which, practically speaking, is more than we’ll ever need in music production.
Record and mix in 24 bit, dither your music down to 16 bit in the case of a CD (due to the comparably limited dynamic range of the medium).

What is Bit Depth – What Bit Depth Should You Use