Audio File Size Calculator
How big a recording will be: uncompressed PCM (WAV, AIFF) from the sample rate, bit depth and channels, or a compressed file (MP3, AAC, Opus) from its bitrate, in decimal and binary units.
Result…
How it's calculated
Uncompressed size (bytes) = sample rate × bit depth × channels × seconds ÷ 8 Compressed size (bytes) = bitrate (kbps) × 1,000 × seconds ÷ 8 1 MB = 1,000,000 bytes; 1 MiB = 1,048,576 bytes
Uncompressed (PCM) audio stores every sample of every channel, so its size is simple multiplication: samples a second, times bits per sample, times channels, times the length, divided by 8 to turn bits into bytes. CD-quality stereo (44,100 Hz, 16-bit, 2 channels) runs at 1,411.2 kbps, about 10.6 MB a minute. Compressed formats such as MP3, AAC and Opus are described by a bitrate instead, so the size is that bitrate times the length. Storage is sold in decimal units (MB, GB), while some operating systems show binary units (MiB, GiB, often still labelled MB and GB), which is why the same file can show two sizes.
Your numbers, step by step
About the Audio File Size calculator
This audio file size calculator tells you how much space a recording will take before you press record. For uncompressed audio such as WAV or AIFF, enter the sample rate, the bit depth, the number of channels and the length, and it multiplies them out: samples a second, times bits per sample, times channels, times seconds, divided by 8 for bytes. For compressed audio such as MP3, AAC or Opus, enter the bitrate instead. Podcasters, musicians, field recordists and video editors use it to plan card space, upload limits and archive storage. The answer comes in decimal units (kB, MB, GB), the way drives and cards are sold, and in binary units (KiB, MiB, GiB), the way some operating systems report sizes, so you can match either. Every multiplication is shown with your numbers, so you can check it against your recorder or encoder settings.
How to use it
- Choose the “Audio type”: “Uncompressed (WAV, AIFF)” or “Compressed (from a bitrate)”.
- For uncompressed audio, enter the “Sample rate” in Hz, pick the “Bit depth” and enter the number of “Channels” (1 for mono, 2 for stereo).
- For compressed audio, enter the “Bitrate” in kbps from your encoder or the file's details.
- Enter the length in “Hours”, “Minutes” and “Seconds”.
- Read the file size in MB and MiB, the data rate in kbps and the size per minute.
Worked example
A 45-minute stereo recording at 48,000 Hz and 24-bit: 48,000 × 24 × 2 = 2,304,000 bits a second (2,304 kbps). Over 2,700 seconds that is 2,304,000 × 2,700 ÷ 8 = 777,600,000 bytes, which is 777.6 MB or about 741.6 MiB, at 17.28 MB a minute. The same 45 minutes encoded at 256 kbps comes to 86.4 MB (about 82.4 MiB), roughly a ninth of the size.
Updated
Questions people ask
How do I calculate the size of a WAV file?
Multiply the sample rate by the bit depth, the number of channels and the length in seconds, then divide by 8 to get bytes. CD-quality stereo (44,100 Hz, 16-bit, 2 channels) works out to 1,411.2 kbps, about 10.6 MB a minute. The file header adds only a few dozen bytes on top.
What is the formula for MP3 file size from bitrate?
Size in bytes = bitrate in kbps × 1,000 × length in seconds ÷ 8. A 4-minute track at 320 kbps is 320,000 × 240 ÷ 8 = 9,600,000 bytes, or 9.6 MB. Variable-bitrate files and embedded cover art make the real file a little different.
Why does my computer show a smaller number than the calculator?
Some systems divide by 1,048,576 (binary MiB) but still label the result MB, while drive makers use 1,000,000 bytes per MB. The calculator shows both, so a 37.04 MB file in decimal units is 35.33 MiB in binary units. You can check the prefixes with NIST's page on binary prefixes, and convert between them with the data storage converter.
Does 24-bit audio take more space than 16-bit?
Yes, exactly half as much again: each sample takes 24 bits instead of 16, so at the same sample rate and channel count the file is 1.5 times the size. Doubling the sample rate from 48,000 to 96,000 Hz doubles the size too.
Is the result exact for FLAC or audio inside a video?
No. FLAC and other lossless formats compress the samples by an amount that depends on the music, so use the uncompressed result as an upper limit. For audio inside a video, add the audio bitrate to the video bitrate in the video bitrate calculator.