Audio File Size Calculator
Estimate how large an audio file will be before you record it. Enter a duration, pick a format, and the page applies the actual bit-rate arithmetic for uncompressed, lossless and compressed audio — with a breakdown showing why a three-minute track is 30 MB as WAV and under 3 MB as a low-rate MP3.
Three Different Formulas Behind One Answer
Audio file size is not one calculation. Uncompressed PCM, lossless compression and lossy compression scale with entirely different inputs, and the page switches formulas depending on the format you choose. That is the reason the sample-rate and bit-depth selectors sometimes appear to do nothing: on a fixed-bit-rate MP3 they genuinely have no effect, because the bit rate already fixes the file size.
- Uncompressed WAV is computed as sample rate x (bit depth / 8) x channels x duration in seconds. Every input on the form changes the answer.
- FLAC is derived from the WAV figure and multiplied by 0.6. Lossless compression ratios vary with the material, so this is an estimate rather than a measurement, and the page says so.
- MP3, AAC and OGG use bit rate x duration / 8. The bit rate is the only thing that matters, so changing sample rate, bit depth or channel count leaves the result untouched.
- Channel count is 1 for mono, 2 for stereo and 6 for the 5.1 surround option, which is why selecting surround multiplies an uncompressed estimate by three.
Sizing a File Before You Record
- Enter the duration in minutes. The field accepts decimals, so a 3-minute 30-second track is entered as 3.5 and a 45-second clip as 0.75.
- Choose a format first, because it decides which of the other three inputs are used. WAV and FLAC respond to sample rate, bit depth and channels; the MP3, AAC and OGG options do not.
- Set the sample rate. 44.1 kHz is the CD standard, 48 kHz is the film and video default, and 96 kHz and 192 kHz are the high-resolution options used in mastering.
- Set the bit depth and channel count if you are estimating WAV or FLAC. These two fields are ignored for the compressed formats.
- Read the result, which is given in bytes together with kilobyte, megabyte and gigabyte equivalents, followed by a plain-text summary you can copy out of the page.
A Three-Minute Track Across Seven Formats
The figures below are what the page returns for a three-minute track at 44.1 kHz, 16-bit, stereo. They are worth reading as a set, because the spread between the largest and smallest is more than tenfold for identical musical content.
- WAV: 31,752,000 bytes, shown as 30.28 MB. This is the raw sample data and nothing else.
- FLAC: 19,051,200 bytes, or 18.17 MB. That is the WAV figure at the assumed 60 percent compression, which is roughly what lossless audio achieves on typical music.
- MP3 at 320 kbps: 7,200,000 bytes, shown as 6.87 MB. This is the highest bit rate the page offers and the one that is hardest to distinguish from the original.
- MP3 at 192 kbps: 4,320,000 bytes, or 4.12 MB. This is the point at which most listeners stop noticing a difference on ordinary equipment.
- MP3 at 128 kbps: 2,880,000 bytes, or 2.75 MB. The largest drop in quality for the smallest saving, which is why it is a poor default for anything you intend to keep.
- AAC at 256 kbps and OGG at 192 kbps land at 5.49 MB and 4.12 MB. The page treats both as constant bit rate, which is a reasonable approximation but not how these codecs actually behave on real material.
- The same three minutes as six-channel WAV comes to 95,256,000 bytes, about 90.84 MB — three times the stereo figure.
Choosing a Format for Your Purpose
| Alternative | Notes |
|---|
| WAV for recording and editing | Any further processing — noise reduction, mixing, level changes — should happen on uncompressed audio. Every lossy encode discards information permanently, and stacked encodes compound the damage. |
| FLAC for archives | Roughly 60 percent of WAV size with no loss at all, which makes it the sensible choice for a library you intend to keep. Support is near-universal on desktop and on Android; Apple devices need a third-party player. |
| MP3 at 256 to 320 kbps for delivery | Playable anywhere, and at these rates the difference from the source is small. Below 192 kbps the artefacts become audible on cymbals, reverb tails and quiet passages. |
| AAC for streaming and mobile | Reaches acceptable quality at a lower bit rate than MP3, which is why streaming services use it. The page's 256 kbps option is a fair stand-in for a typical stream. |
| OGG for open toolchains | Comparable to AAC in efficiency and free of licensing requirements, which matters for game audio and open-source distribution. |
Where the Estimate Diverges From Reality
An estimate is useful precisely because you know which way it can be wrong. Four things push real files away from the numbers on the page.
- The megabyte shown is 1024-based, so it is what operating systems display rather than what the decimal prefix strictly means. A drive advertised in decimal gigabytes will hold slightly fewer of these than the arithmetic suggests.
- Fixed-bit-rate formats are the exception in modern encoders. VBR MP3 chooses a bit rate per frame, so a real file of an acoustic recording can come in well under the estimate while a dense mix comes in over it.
- FLAC compression is material-dependent. Silence and simple tones compress far better than 60 percent, while heavily layered noise can compress worse.
- Container overhead is not modelled. Headers, ID3 tags with embedded artwork, and chapter data can add a few hundred kilobytes, which is negligible on a WAV and significant on a short low-rate MP3.
Audio Size Questions
Why does changing the sample rate do nothing when MP3 is selected?
Because a fixed-bit-rate MP3 is defined by its bit rate. 320 kbps means 320,000 bits for every second of audio regardless of what the source sample rate was, so the file size is fully determined by duration. Sample rate still affects how the encoder allocates those bits, and therefore the quality, but not the size. The same applies to AAC and OGG here.
How accurate is the FLAC figure?
It is an estimate built on an assumed 60 percent compression ratio. Real lossless audio on typical music lands between about 50 and 70 percent of the original, so treat the number as a planning figure. If the exact size matters, encode a minute and extrapolate.
Is there an upload or an account?
No. There is nothing to upload — the whole page is a set of arithmetic operations on numbers you type, executed in the browser. No audio ever passes through a server, no account is required, and the page keeps working with the network disconnected.
How long can I record into a given amount of space?
Work backwards from the formula. For WAV, divide your free space in bytes by the product of sample rate, bit depth divided by eight and channel count to get seconds. For a compressed format, divide by the bit rate in bits per second instead, after multiplying your free space by eight.
Last verified: October 3, 2026
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Maintained by Huang Bin · Last updated October 3, 2026