Audio File Size Calculator

This utility calculates the size of audio files (both uncompressed, PCM/IEEE FP audio, such as “.WAV”, “.W64” “.AIFF/.AIF” and also compressed files such as MP3, WMA, AAC and OGG Vorbis), according to the recording duration and file settings you choose:

**N.B.** If you’re looking for a calculator to do the opposite (i.e. calculate duration from available space), then go here.

Audio File Size Calculator by Colin Crawley
Settings - Uncompressed (WAV, AIFF etc.)
Settings - Compressed (MP3, AAC etc.)
Uncompressed (WAV, AIFF etc.) 1411.2 kbps


Compressed (MP3, AAC etc.) 0 kbps



Enter the duration of your file in hours, minutes, seconds and milliseconds. Calculating the size of uncompressed files also requires the Sample Rate, Bit Depth and Channel information (but not the Bit Rate, which is automatically calculated). In addition to the duration, calculating the size of compressed files such as MP3 etc., requires only the Bit Rate information (in this case the Sample Rate, Bit Depth and Channel information is ignored).  For compressed files encoded with CBR (Constant Bit Rate), the displayed file size should be as accurate as possible (notwithstanding variables such as header information etc- see below). For compressed files encoded with VBR (Variable Bit Rate), the displayed file size can be slightly less accurate because in this case the bit rate can vary depending on the programme material.

Note that the file size reported by your device may vary slightly from that shown due to file allocation methods, possible differences in the amount of header information and/or the fact that some operating systems calculate hard disk space differently from others (e.g., some calculate it in binary and call 1kB 1024 bytes whilst others – and most hard drive manufacturers – calculate it in decimal and call 1kB 1000 bytes) – this calculator handles both methods.

If you find this useful and/or have any comments or suggestions then do let me know via the comment section below.


42 thoughts on “Audio File Size Calculator”

  1. Hey, I’m wondering how you developed the algorithm to predict the compressed file size from the uncompressed file size and the other parameters, I’ve been researching for hours upon hours and I can’t find anything online to point me in the right direction to understand how these approximations have been made! I’m wondering if you have any resources you could point me to?

      1. This is wonderful method. I want to trim a file having Duration: 1.22.17 bit rate : 47kbps size: 28.2 mb size : 29,597,696bytes, such that it becomes less than 16 mb file, How can I use your method. as a layperson I have this issue. thanks

        1. Hello Krish,

          If you enter the figures you quote into the calculator above you’ll see that you would need to reduce the bit rate of your compressed file from 47 kbps down to 25 kbps in order to keep it under 16 MB in size.

          Two things to note though:

          1. Is this really an audio file? If so, 47 kbps is extremely low (even for a lossy compressed format) and would likely represent pretty poor audio quality. Reducing it further may even render it useless.

          2. If you really must lower the bit rate, then you should convert the file again (but with the new settings) from the original, uncompressed audio file. Converting an already lossy compressed file again will reduce its quality even further.

  2. Thanks for this Colin. I’m trying to do a “sanity check” on some file conversions using `ffmpeg`. What would make it more useful for me is if it included specific audio formats, and their compression ratios. I realize the compression is not a constant, but it doesn’t vary wildly either. The values given on the following website are consistent with my limited experience on this subject:

    1. Hello Seamus,

      Thanks for your message and I’m glad you find my calculator useful.

      Thank you also for your suggestion. However, I feel it’s beyond the scope of this calculator to include additional specific formats and their compression ratios because AFAIK, the compression ratio of most formats (both lossy, with the exception of those which have a CBR option, and lossless) is programme-dependent and doesn’t vary hugely anyway. In general, I would need to be convinced that adding any functionality would increase the calculator’s value for a majority of users.

    1. Perhaps you’re looking at the “Uncompressed” (instead of the “Compressed”) output? When I enter 5min 17secs at 320kbps into my calculator I see a result of 12.68 MB (under the decimal “Compressed” result), which is correct.

      …unless I’ve misunderstood you (sorry if that’s the case). If you’re saying that you have an mp3 of 5min 17secs that is, in fact 28 MB in size, then I can only guess that it must be padded out with data extraneous to the audio (e.g. tons of extra metadata, or even just zeros!). Why that might be is anyone’s guess though.

      1. Yes, the actual file is that large. I guess I will need to look into the tags but I didn’t see anything suspicious by glancing at the file. I even removed 5mb of artwork and it’s still that big!

  3. I think the binary (2^10) to decimal (1000) converter is off. It just multiplies by 1.024, but that only works for KiB -> kB. For MiB -> MB it needs 1.024^2, for GiB -> GB 1.024^3, and so on, given that the binary prefix equivalent is 2^(10*n/3), where n is the power in 10^n.

  4. im trying to find out how often my RME is recording a sample pr second, im using 192 khz in 24 bit, how do I do that?

    I saw somewhere its every 2 ms, but I don’t think that’s right ?

    1. Hello Kim,

      Since your audio interface is set to record at a sample rate of 192kHz per second, then it is converting audio at a rate of 192000 samples per second.

      For specific information about your hardware, I suggest you contact RME directly.

    2. hi

      yes that’s in a full second but digital sampling doesn’t record all the time, as analog does, I think I got it now – 1/192000 x 1000 = 0,0052083333333333

      so that means it take a sample every 5 ms, someone correct me if im wrong 🙂

      1. Hi Kim,

        No, it’s MUCH more frequent than that – a sample taken only once every 5 milliseconds would result in a very inaccurate (and audibly chopped-up) digital representation of the audio!

        You have the correct calculation but you’re interpreting the result incorrectly (i.e. the result is in milliseconds, not in seconds). In fact, a simpler way to express this calculation would be 1/192 (because one second = one thousand milliseconds). Either way, the result is 0.005208333 milliseconds which is, of course, a tiny, tiny fraction of one millisecond.

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