Why does the compressed size not depend on the sample rate?

Because a lossy encoder is given a bitrate target and adjusts whatever it must to meet it. Rate, channels and depth affect how much the encoder has to throw away, not how many bits per second come out, so the file size follows the bitrate and the duration alone.

How accurate is the uncompressed figure?

The sample arithmetic is exact, since it is the number of samples multiplied by the bytes each occupies. The file on disk will be slightly larger because of the header, which is a fixed few dozen bytes and therefore negligible for anything but a fraction of a second of audio.

What about a lossless compressed format?

It sits between the two figures shown. Lossless compression typically removes twenty to fifty percent of the size of PCM depending on how compressible the signal is, with quiet or highly periodic material shrinking the most. The two results here bracket it rather than estimating it.

Why does doubling the sample rate double the size?

Because twice as many samples are stored for the same duration, each taking the same number of bytes. The same is true of the channel count, which is why an uncompressed surround file is three times the size of a stereo one at the same rate and depth.

Can I use this to work out how much space a session will need?

For the recorded audio, yes, though a real session also holds alternate takes, edits and often several versions of each track. Estimating from the final duration and then multiplying by the number of tracks and takes gives a more realistic working figure than the finished length alone.

Audio File Size Calculator

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Audio File Size Calculator estimates how large a recording will be, both uncompressed and at a lossy bitrate. It answers the practical question of whether a project will fit.

What is Audio File Size Calculator?

Set the duration and the format parameters and the panel gives two sizes side by side, along with how much smaller the compressed version is.

The inputs and the two results:

A duration in minutes from a tenth to six hundred, defaulting to three.
A sample rate chosen from seven standard values between twenty two thousand and fifty and one hundred and ninety two thousand hertz.
A channel count of mono, stereo or six channels for surround.
A bit depth of eight, sixteen, twenty four or thirty two bits.
A lossy bitrate from ninety six to three hundred and twenty kilobits per second, defaulting to the highest.
Two results, one for the uncompressed file and one for the compressed estimate, plus the ratio between them.

The two calculations are different in kind. For uncompressed PCM the size is the duration multiplied by the sample rate, the channel count and the depth in bytes, which is exact rather than approximate: a three minute stereo recording at forty four thousand one hundred hertz and sixteen bits comes to about fifteen megabytes, and the arithmetic is simply the number of samples times the bytes each one takes. For a lossy format the size is the bitrate multiplied by the duration, divided by eight to convert bits into bytes, and it does not depend on the sample rate, the channel count or the depth at all, because a lossy encoder has already thrown away whatever it needed to in order to hit its target. That is why the same three minutes comes to about seven megabytes at three hundred and twenty kilobits per second regardless of the source format. The ratio line is the interesting comparison, since it is the whole reason lossy formats exist: a typical result is somewhere between two and three times smaller, and a low bitrate can be an order of magnitude smaller again. The compressed figure is deliberately described as an estimate because a lossy file carries headers, tags and frame padding, and its real size depends on the encoder's decisions, so the arithmetic gives the payload rather than the file on disk.

Where the estimate is rough:

The compressed figure excludes container overhead, metadata and tag data.
No encoder efficiency differences are modelled; only the target bitrate matters.
Variable bitrate files will differ from the constant rate figure.
Lossless compressed formats such as FLAC are not estimated, though they sit between the two.
No consideration of how much content the file actually has.
Nothing is uploaded, and no file is measured.

Use it to plan storage before a session, to decide whether a project fits on a drive, or to see what a format choice costs in size. When the question is how much data a stream carries rather than how much a file weighs, the streaming bitrate calculator works in bandwidth and monthly transfer instead, and when the parameters themselves need understanding rather than combining, the sample rate calculator and the bit depth calculator explain what each one buys.

How to use Audio File Size Calculator

Enter the length of the material in minutes.
Choose the sample rate, channel count and bit depth for the uncompressed figure.
Choose a lossy bitrate for the compressed figure.
Compare the two sizes and the ratio between them.

When to use Audio File Size Calculator vs related tools

Audio File Size Calculator is the tool for working out whether a recording will fit, and what each format choice costs in space. Streaming Bitrate Calculator covers the other direction, where the concern is bandwidth over a network rather than storage on a disk. Sample Rate Calculator and Bit Depth Calculator explain the two parameters that drive the uncompressed figure, and Audio Bitrate Reference is the table to read when choosing a bitrate rather than calculating what it costs.

Privacy & Security

This tool runs entirely in your browser — no data ever leaves your device. There is no server round-trip, no upload, no logging, and no account required. Your input is processed locally using client-side JavaScript and is never stored, transmitted, or accessible to anyone else. When you close the tab, everything disappears.