Digital audio is stored as a long list of numbers. The sample rate says how many measurements of the sound wave are taken each second (44,100 for a CD), and the bit depth says how many bits describe each measurement (16 bits for a CD gives 65,536 levels). Every channel (left and right for stereo, six for 5.1 surround) is stored separately, so the data rate is simply the product of the three numbers.
Because uncompressed PCM audio has no tricks to shrink it, its size grows strictly with time: one minute of CD-quality stereo takes about 10.6 MB, while a 24-bit/96 kHz studio recording needs more than three times as much. Lossy codecs such as MP3, AAC and Opus throw away detail the ear is unlikely to notice and are described only by their bitrate, while lossless FLAC or ALAC usually saves 40–60% without losing anything.
Use the calculator to plan recording sessions, estimate how much a podcast or audiobook will take on disk, check upload limits or compare formats before exporting.
How to use the Audio File Size Calculator
- Sample rate
- Bit depth
- Channels: 1 = mono, 2 = stereo, 6 = 5.1 surround, 8 = 7.1 surround.
- Duration
- Compressed bitrate (for comparison): MP3 128–320 kbps, AAC 256 kbps (streaming stores), Opus 96–160 kbps.
Results update as you type, every field has its own unit menu, and everything is calculated in your browser.
How it works
The calculator multiplies sample rate, bit depth and channel count to get the PCM bit rate, multiplies by the duration in seconds and divides by eight to convert bits to bytes. The compressed size uses the stated bitrate in the same way. Sizes are shown in decimal megabytes by default; choose MiB or GiB to match what Windows shows.
Worked example
A 5-minute stereo song recorded at 44.1 kHz and 16 bits has a bit rate of 44,100 × 16 × 2 = 1,411,200 bit/s (1,411.2 kbps). Over 300 seconds that is 1,411,200 × 300 = 423,360,000 bits, or 52,920,000 bytes = 52.92 MB (50.47 MiB). The same song as a 320 kbps MP3 needs 320,000 × 300 ÷ 8 = 12,000,000 bytes = 12 MB, and a typical FLAC about 29 MB.
Size per minute for common formats
| Format | Bitrate | Per minute |
|---|---|---|
| Telephone speech, 8 kHz/8-bit mono | 64 kbps | 0.48 MB |
| CD, 44.1 kHz/16-bit stereo | 1,411.2 kbps | 10.58 MB |
| Video, 48 kHz/24-bit stereo | 2,304 kbps | 17.28 MB |
| Studio, 96 kHz/24-bit stereo | 4,608 kbps | 34.56 MB |
| Hi-res, 192 kHz/24-bit stereo | 9,216 kbps | 69.12 MB |
| 5.1 film, 48 kHz/24-bit | 6,912 kbps | 51.84 MB |
| MP3 320 kbps | 320 kbps | 2.4 MB |
| AAC 256 kbps | 256 kbps | 1.92 MB |
Inputs explained
| Field | What to enter |
|---|---|
| Sample rate | Choose one: 8 kHz (telephone), 16 kHz (wideband speech), 22.05 kHz, 32 kHz … |
| Bit depth | Choose one: 8-bit, 16-bit (CD quality), 20-bit, 24-bit (studio) … |
| Channels | A number. 1 = mono, 2 = stereo, 6 = 5.1 surround, 8 = 7.1 surround. |
| Duration | Units: min, s, h |
| Compressed bitrate (for comparison) | In kbps. MP3 128–320 kbps, AAC 256 kbps (streaming stores), Opus 96–160 kbps. |
What each result means
- Uncompressed size (WAV / AIFF) = [Sample rate]×[Bit depth]×[Channels]×[Duration]÷8
- Uncompressed bitrate = [Sample rate]×[Bit depth]×[Channels]÷1000
- Compressed size at the chosen bitrate = [Compressed bitrate (for comparison)]×1000×[Duration]÷8
- Typical lossless FLAC size (about 55% of WAV) = [Uncompressed size (WAV ÷ AIFF)]×0.55
- Uncompressed size per minute = [Sample rate]×[Bit depth]×[Channels]×60÷8
- Highest frequency captured (Nyquist) = [Sample rate]÷2÷1000
- Theoretical dynamic range = 6.02×[Bit depth] + 1.76
Formula
Bit rate = sample rate × bit depth × channels
File size (bytes) = bit rate × duration (s) ÷ 8
Compressed size = bitrate (kbit/s) × 1000 × duration ÷ 8
Worked example
Inputs: Sample rate: 44.1 kHz (CD); Bit depth: 16-bit (CD quality); Channels: 2; Duration: 5 min; Compressed bitrate (for comparison): 320 kbps.
Results: Uncompressed size (WAV / AIFF) = 52.92 MB; Uncompressed bitrate = 1,411.2 kbps; Compressed size at the chosen bitrate = 12 MB; Typical lossless FLAC size (about 55% of WAV) = 29.11 MB; Uncompressed size per minute = 10.58 MB; Uncompressed ÷ compressed size = 4.41 ×; Highest frequency captured (Nyquist) = 22.05 kHz; Theoretical dynamic range = 98.1 dB.
Key terms
- Sample rate
- Number of samples taken per second, in hertz (44,100 Hz for CD).
- Bit depth
- Number of bits stored per sample; each extra bit adds about 6 dB of dynamic range.
- Bitrate
- Amount of data per second of audio, in kilobits per second (kbps).
- Nyquist frequency
- Half the sample rate, the highest frequency that can be recorded without aliasing.
- Lossless compression
- Formats such as FLAC and ALAC that shrink the file but restore every original sample.
Frequently asked questions
How big is one minute of CD-quality audio?
44,100 × 16 × 2 × 60 ÷ 8 = 10,584,000 bytes, about 10.6 MB (10.1 MiB).
How large is a 5-minute 16-bit/44.1 kHz stereo WAV?
52.92 MB: the bit rate is 1,411.2 kbps and 1,411,200 × 300 ÷ 8 = 52,920,000 bytes.
How much smaller is a 320 kbps MP3?
About 4.4 times smaller than CD-quality WAV: 1,411.2 ÷ 320 = 4.41, so 4 minutes take 9.6 MB instead of 42.3 MB.
Why does my computer show a smaller number?
Windows reports sizes in binary units (1 MiB = 1,048,576 bytes) but labels them “MB”. Switch the result unit to MiB to match.
Does the file header add size?
Yes, but only a few dozen bytes to a few kilobytes for metadata and cover art, negligible for music files.
Is 24-bit better than 16-bit?
It gives more headroom when recording (about 146 dB vs 98 dB theoretical dynamic range); for listening, 16-bit is already beyond what most rooms and ears can use.
How big is FLAC compared with WAV?
Usually 50–70% of the WAV size, depending on the music; quiet, simple recordings compress better.