ConverterHub

Audio File Size Calculator

Know your audio file size before you export

How it is calculated

The tool takes the bitrate in kilobits per second (kbps) and the duration in minutes:

bytes = bitrate × 1000 / 8 × (minutes × 60) and size (MB) = bytes / (1024 × 1024)

Dividing by 8 turns bits into bytes, and the result is shown in binary megabytes (1 MB = 1,048,576 bytes), rounded to two decimals. Both values must be greater than zero, otherwise no result is shown. The figure assumes constant bitrate (CBR) audio; variable-bitrate files will land near it, and container headers and tags add a little extra.

Worked example

A one-hour podcast encoded at 128 kbps: 128 × 1000 / 8 = 16,000 bytes per second. One hour is 60 × 60 = 3,600 seconds, so the file holds 16,000 × 3,600 = 57,600,000 bytes. Dividing by 1,048,576 gives 54.93 MB.

Try this example →

Common mistakes

  • Entering the duration in seconds or hours; the field expects minutes, so a 90-second clip is 1.5, not 90.
  • Typing the bitrate in bps or Mbps instead of kbps (320 kbps, not 320000).
  • Confusing bits and bytes: a 128 kbps file is 16 kilobytes per second, not 128.
  • Expecting this to work for uncompressed WAV; that size depends on sample rate, bit depth and channels, so use the equivalent bitrate (for example 1411 kbps for CD-quality stereo).
  • Comparing against a platform limit quoted in decimal MB (1,000,000 bytes) when this result is in 1,048,576-byte units.

About this calculator

This calculator estimates a compressed audio file's size using size = (bitrate × duration) / 8, converting bits per second to bytes, since bitrate for formats like MP3 and AAC is specified as the number of bits used to encode each second of audio regardless of the file's sample rate or bit depth. A higher bitrate spends more bits per second on the encoding, producing better fidelity at the cost of a larger file — the trade-off every lossy audio format is built around.

Podcasters and musicians use this before exporting to predict whether a file will fit a hosting platform's upload limit or a client's email attachment size, and audio engineers use it to plan storage and bandwidth for a batch of episodes or tracks before committing to a bitrate for the whole project.

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