Sample Rate and Bit Depth for Mastering

What the two numbers mean

Sample rate is how many times per second the signal is measured. The highest frequency a rate can represent is half of it, the Nyquist frequency: 22.05 kHz for 44.1 kHz. CD audio sets the practical upper limit at 20 kHz to leave room for the anti-aliasing filter.

Bit depth is how finely each sample's level is stored, and it sets the noise floor. A 16-bit file has a theoretical dynamic range of about 96 dB, a 24-bit file about 144 dB. For a full-scale sine wave the theoretical signal-to-noise ratio is 98.09 dB at 16 bits and 146.26 dB at 24 bits.

What each destination asks for

Destination	Sample rate	Bit depth	What the source says
CD (Red Book, IEC 60908)	44.1 kHz	16-bit	stereo linear PCM
Spotify (delivery)	44.1 kHz or higher	24-bit if that is the native master; 16-bit only if no higher one exists	FLAC preferred, WAV accepted; keep the original rate and bit depth; Spotify downsamples higher rates itself
Spotify (lossless playback)	up to 44.1 kHz	up to 24-bit	files below 16-bit or 44.1 kHz are not eligible for lossless playback
Apple Music (Apple Digital Masters)	highest native sample rate	24-bit sources	upsampling does not add information

Most releases reach the stores through a distributor, so check the distributor's upload requirements as well.

44.1 kHz or 48 kHz?

Both rates capture the full audible range. 44.1 kHz is the CD rate and the minimum Spotify accepts; 48 kHz is the usual rate for video work. The practical rule is to choose the rate when the project starts and keep it to the end: every sample-rate conversion is a processing step.

If a song was made at 48 kHz, deliver it at 48 kHz. Spotify asks you not to downsample a master made above 44.1 kHz and converts it itself. Apple asks for the highest native rate and warns that upsampling a 44.1 kHz file to 96 kHz does not recover or add information.

16-bit, 24-bit and dither

Deliver 24-bit when the master exists at 24-bit; both Spotify and Apple ask for it. Reduce to 16-bit only when the destination requires it, as a CD does.

When the bit depth is reduced, the rounding error becomes distortion on quiet material. Dither, a small amount of added noise before the reduction, turns that distortion into a steady noise floor. Apple describes it as a tradeoff: less distortion for slightly more noise. Dither is the very last step, after the limiter, and is generally not needed when the result stays 24-bit.

Where 32-bit float fits

32-bit floating point is a working format. Levels above 0 dBFS are stored without clipping inside the file, which makes it safe for mixdowns and intermediate bounces. The clipping happens later, if the file is converted to fixed point (16 or 24-bit) without lowering the level first.

For delivery, check what the destination lists. Spotify's delivery page describes 16-bit and 24-bit files, so convert a float master to 24-bit, at a level that keeps true peak below your ceiling, before upload.

Recommended settings

Record and mix: 24-bit or 32-bit float, at 44.1 or 48 kHz, chosen once.
Master: at the project rate.
Streaming delivery: 24-bit WAV or FLAC at the native rate.
CD: 44.1 kHz, 16-bit, with dither as the last step.

Quantara exports WAV, FLAC and MP3 in the bit depths your plan includes; a free account includes one free export per account (MP3 320, with a watermark), no card required. Open the studio.

Frequently asked questions

Is Spotify 44.1 or 48 kHz?

Spotify accepts files at 44.1 kHz or higher and plays lossless at up to 24-bit / 44.1 kHz. If your master is above 44.1 kHz, Spotify asks you not to downsample it; it converts the file itself.

Should I upsample my master to 96 kHz?

No. Apple notes that upsampling does not recover or add information to an audio file, and asks for the highest native sample rate instead.

Do I need dither when exporting 24-bit?

Generally no. Dither matters when the bit depth is reduced, typically to 16-bit for CD, and it is applied as the very last step.

Is 16-bit enough for a master?

A 16-bit file has a theoretical dynamic range of about 96 dB, which is what CD uses. For streaming delivery, Spotify and Apple both ask for 24-bit when the master exists at 24-bit.