Audio File Size Calculator
File size of an audio recording
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Need a fast answer on file size of an audio recording? Audio File Size Calculator answers with the steps beside it. You supply Duration (min) and Bitrate (kbps) to Audio File Size; the answer follows at once. Every Audio File Size answer can be reproduced by hand. Anyone comparing options in Tech & Digital can use Audio File Size to compare scenarios. Audio File Size is privacy-first: Tech & Digital inputs stay offline. Audio File Size handles audio file size calculator bitrate duration wav mp3 the same way as free online audio file size calculator — one of the Tech & Digital tools on CalcProMaster. Start with Audio File Size; the first number takes seconds.
What the defaults give
60 minutes at 128 kbps is 56 MB, which is a little under one megabyte per minute of audio.
The tool divides by 1,024 twice, so it reports binary megabytes (MiB) — the unit a file manager shows. Vendors quote decimal megabytes, about 5% smaller.
The formula
MB = kbps × minutes × 60 ÷ 8 ÷ 1,024
A bitrate is kilobits per second, so one minute at 128 kbps carries 128 × 60 = 7,680 kilobits. Dividing by 8 gives 960 kilobytes, and dividing by 1,024 converts to megabytes. Because the arithmetic is linear, size is just bitrate multiplied by time — nothing else enters the calculation.
Worked examples
60 min at 128 kbps → 56 MB
30 min at 128 kbps → 28 MB
120 min at 128 kbps → 113 MB
60 min at 64 kbps → 28 MB
60 min at 256 kbps → 113 MB
Halving the bitrate halves the file at the same length, and doubling the length doubles it at the same bitrate. The two controls are interchangeable in that sense, which is why a long low-bitrate podcast can weigh the same as a short high-bitrate one.
Typical bitrates
Speech compresses well: a 96 kbps mono podcast is 31.6 MB for 45 minutes, and 64 kbps is enough for audiobook narration. Music needs more. A four-minute track at 320 kbps is 9.4 MB, and the same track at 128 kbps is 3.8 MB — the quality difference is audible on good headphones, mostly in cymbals and reverb tails.
Uncompressed CD audio is 1,411 kbps (44.1 kHz, 16-bit, two channels), so the same hour is 620 MB. That is eleven times the 128 kbps MP3, which is the whole reason WAV masters are not what you carry around.
Where the estimate drifts
The tool counts audio payload only. ID3 tags, embedded cover art (often 100–500 KB per image) and chapter data sit on top, and a container such as M4A adds a little more. Variable-bitrate files hold an average rather than a fixed rate, so the real size lands a few percent either side of the prediction.
For a hard limit — a voice-note attachment cap or a memory card for a recorder — add 5% to the result and round up.
Frequently Asked Questions
How big is an hour of 128 kbps audio?
56 MB. At 64 kbps the same hour is 28 MB, and at 256 kbps it is 113 MB.
Why 1,024 rather than 1,000?
The tool reports binary megabytes, the unit file managers show. Storage vendors use 1,000-based megabytes, so a 56 MiB file is sold as roughly 59 MB.
Does the format change the answer?
Not if the bitrate is the same. MP3, AAC and Ogg at 128 kbps all produce the same payload size; they differ in how good they sound at that rate.
What about a WAV file?
Uncompressed CD-quality audio is 1,411 kbps, so an hour is 620 MB. Bitrate is the input, so set it to 1,411 rather than guessing from the extension.
How much does cover art add?
A single embedded image is usually 100–500 KB. An album of twelve tracks can carry several megabytes of artwork that this calculator does not count.
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