Audio File Size Formula: Calculate Uncompressed Audio

The audio file size formula estimates how much storage uncompressed digital audio needs from its duration, sample rate, bit depth, and number of channels. Enter those values to get an estimated size in bytes, with decimal megabytes and binary mebibytes for comparison.

Formula

For uncompressed pulse-code modulation (PCM) audio, the basic estimate is:

File size in bytes = duration in seconds × sample rate in samples per second × bit depth in bits per sample × number of channels ÷ 8

• Duration: audio length in seconds.
• Sample rate: samples recorded per second, measured in hertz (Hz).
• Bit depth: bits used for each sample of each channel.
• Channels: 1 for mono, 2 for stereo, or more for multichannel audio.

Dividing by 8 converts bits to bytes, because one byte contains 8 bits. To express the result as decimal megabytes (MB), divide bytes by 1,000,000. To express it as binary mebibytes (MiB), divide by 1,048,576 (1,024²). Storage systems and software may label binary quantities as “MB” or “GB,” so the displayed unit can vary even when the underlying size does not.

Worked Example

With the calculator’s defaults—60 seconds, 44,100 Hz, 16 bits per sample, and 2 channels—the calculation is:

1. Samples per channel: 60 × 44,100 = 2,646,000.
2. Bits for all channels: 2,646,000 × 16 × 2 = 84,672,000 bits.
3. Convert to bytes: 84,672,000 ÷ 8 = 10,584,000 bytes.
4. Decimal size: 10,584,000 ÷ 1,000,000 = 10.58 MB.
5. Binary size: 10,584,000 ÷ 1,048,576 = 10.09 MiB.

This is the audio data size before container headers, metadata, or other file-specific information. A saved file can be slightly larger.

When to Use the Calculation

This formula is useful for estimating storage or transfer needs when audio is uncompressed, or for understanding how recording settings affect the amount of data generated. It can also help compare two PCM recording configurations without relying on a particular program’s file-size display.

For example, one hour of stereo PCM at 48,000 Hz and 24 bits per sample is estimated as:

3,600 × 48,000 × 24 × 2 ÷ 8 = 1,036,800,000 bytes, or about 1,036.80 MB (about 988.77 MiB).

At the same duration, rate, and bit depth, mono requires half as much audio data as stereo because it has one channel instead of two. Doubling the sample rate or bit depth also doubles the uncompressed data size, if all other settings remain unchanged.

Uncompressed and Compressed Audio

The formula gives a direct estimate for uncompressed PCM data, such as the audio payload commonly used in WAV or AIFF files. It does not predict the exact size of a compressed file. Lossless formats reduce repeated or predictable information while preserving the audio signal; lossy formats discard some information to reduce size. Their resulting file sizes depend on the encoding method and settings.

For constant-bitrate compressed audio, a useful estimate is:

Size in bytes ≈ bitrate in bits per second × duration in seconds ÷ 8

For instance, 60 seconds encoded at 128 kilobits per second (128,000 bits per second) is approximately 960,000 bytes, or 0.96 MB, before container overhead. With variable-bitrate encoding, the bitrate changes across the recording, so duration and a target or average bitrate provide only an estimate. The PCM formula should not be used as if it were an exact compressed-file calculator.

Reading Results and Avoiding Mistakes

• Use seconds consistently. Convert minutes to seconds by multiplying by 60, and hours to seconds by multiplying by 3,600.
• Distinguish bits from bytes. Bit depth is measured in bits per sample; file sizes are commonly shown in bytes. Omitting the division by 8 makes the answer eight times too large.
• Count channels correctly. Stereo means two channels. A multichannel recording’s channel count applies to every sample time.
• Do not confuse sample rate and bitrate. Sample rate is samples per second per channel. Bitrate is the total data rate, usually expressed in bits per second.
• Keep unit labels clear. MB is decimal; MiB is binary. A difference between displayed values may be a unit convention, not a calculation error.

The result is an estimate of audio sample data, not necessarily the exact size shown by a file manager. Headers, metadata, padding, and format-specific structures add overhead. For very short files, that overhead can be a noticeable share of the total. Rounding the displayed answer also hides small differences, so use the byte result when comparing precise estimates.

Frequently Asked Questions

How do you calculate an audio file size?
For uncompressed PCM, multiply duration in seconds by sample rate, bit depth, and channel count, then divide by 8 to convert bits to bytes.

How large is one minute of CD-quality audio?
At 44,100 Hz, 16-bit depth, and stereo, one minute is about 10,584,000 bytes: 10.58 MB or 10.09 MiB, before file overhead.

Does stereo audio take twice the space of mono?
For uncompressed audio with the same duration, sample rate, and bit depth, yes. Stereo has two channels, so its audio data is twice the size of mono.

Why is my audio file larger than the formula’s answer?
The formula estimates the uncompressed audio payload. A file may also include a header, metadata, and other format information, which adds bytes.

Can this formula calculate an MP3 or other compressed file?
Not exactly. For constant-bitrate audio, estimate size as bitrate × duration ÷ 8. Variable-bitrate files need the actual average bitrate or a file-size reading for an exact answer.

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in duration | Duration | s | 60 | 0
in rate | Sample rate | Hz | 44100 | 0
in depth | Bit depth | bits/sample | 16 | 0
in channels | Channels | - | 2 | 0
out bytes | Uncompressed size | bytes | duration * rate * depth * channels / 8 | 0
out mb | Decimal size | MB | bytes / 1000000 | 2
out mib | Binary size | MiB | bytes / 1048576 | 2