What this Audio File Size Calculator does
The Audio File Size Calculator estimates the storage required for uncompressed pulse-code modulation (PCM) audio. It uses four settings: duration, sample rate, bit depth, and channel count. The calculation multiplies the number of seconds by the number of samples captured per second, the bits used for each sample, and the number of channels. It then converts bits to bytes and bytes to decimal megabytes.
This is useful during content and media production when planning recording sessions, choosing export settings, estimating upload sizes, or checking whether a project will fit within available storage. For example, a producer can compare a short stereo voice recording with a longer multichannel field recording before transferring files or organizing a project drive.
The result is an estimate for uncompressed PCM data. It does not predict the exact size of MP3, AAC, FLAC, or another encoded file. Those formats use compression and their sizes depend on codec settings and, in some cases, the audio content itself. Treat this result as a planning figure for raw PCM audio, not as a guaranteed export size.
How to use the Audio File Size Calculator
Enter the audio duration in seconds, then provide the sample rate, bit depth, and number of channels. The controls allow values from 1 to 86,400 seconds, 8,000 to 192,000 Hz, 8 to 32 bits per sample, and 1 to 8 channels. Choose values that describe the recording or production format you are evaluating.
- Duration is the length of the audio in seconds. Convert minutes to seconds before entering them. A two-minute clip is 120 seconds.
- Sample rate is the number of audio samples captured each second, measured in hertz. Enter the rate used by the recording or session.
- Bit depth is the number of bits used to represent each sample. Use the setting associated with the PCM file you are estimating.
- Channels is the number of separate audio channels. Mono uses one channel, stereo uses two, and multichannel audio uses the relevant channel count.
For a worked example, consider 60 seconds of stereo audio at 48,000 Hz and 24 bits per sample. Applying the calculator's formula gives 60 × 48,000 × 24 × 2 ÷ 8 ÷ 1,000,000 = 17.28 MB. The calculation first produces bytes, then divides by one million to express the result in decimal megabytes.
How the Audio File Size Calculator formula works
For uncompressed PCM, each channel contributes one sample value at every point in time. Multiplying duration by sample rate gives the number of samples per channel. Multiplying that count by bit depth gives bits per channel. Multiplying by channel count accounts for all channels in the file.
The resulting bit count is divided by eight because one byte contains eight bits. The byte count is divided by 1,000,000, so the reported unit is decimal megabytes (MB). This unit convention is common in storage and file-size labeling. A mebibyte (MiB) uses 1,048,576 bytes, so a value shown in MB will be numerically different from the same byte count expressed in MiB.
The formula can be written as:
Size in MB = duration in seconds × sample rate in Hz × bit depth in bits × channels ÷ 8 ÷ 1,000,000
For the default settings of 60 seconds, 48,000 Hz, 24 bits, and two channels, the same arithmetic produces 17.28 MB. The formula assumes continuous PCM samples with no additional container overhead, metadata, padding, or headers. Those additions are generally small relative to long recordings, but the exact file can differ.
Use cases for an audio file size estimate
Estimating uncompressed audio size can help with practical production decisions before recording or rendering begins. The estimate makes it easier to reason about storage and transfer needs in a consistent way.
- Session planning: Estimate the raw storage needed for a set of takes or a long recording session. Multiply the result for one file by the expected number of similar files to get a rough project total.
- Recording format comparisons: See how changing sample rate, bit depth, or channel count affects PCM storage. Increasing any of these values increases the estimated size in direct proportion.
- Media handoff: Prepare for moving audio between a recording location, an editing workstation, and an archive. A raw PCM estimate can help with broad transfer planning.
- Multichannel production: Compare a mono source with stereo or a larger channel layout. The channel count is an explicit multiplier, so doubling channels doubles the estimate when the other inputs remain the same.
- Archive sizing: Build an initial storage estimate for uncompressed masters. Include all expected recordings and account separately for backups, alternate versions, and other project assets.
These uses rely on the same assumptions. If you are estimating a compressed delivery format, consult the export settings or codec documentation for a more suitable method.
Factors that affect the final audio file size
Duration, sample rate, bit depth, and channel count determine the calculator's result. The relationship is linear: doubling the duration doubles the estimated size, and doubling one of the format values has the same effect. A 30-second file with other settings unchanged is half the size of a 60-second file.
Actual files may include headers, metadata, and container information. Some recording or editing workflows also store additional data, such as alternate takes or embedded markers. These details are outside the formula. If exact storage use matters, export a representative file with the intended software and inspect its reported size.
Compression changes the calculation substantially. Lossy formats such as MP3 and AAC commonly use a target bitrate, so duration and bitrate are the central inputs for a simple estimate. Lossless compression such as FLAC varies with the material and encoder settings. Neither can be derived faithfully from the four PCM inputs alone. The calculator therefore remains focused on uncompressed PCM, where the relationship is direct and transparent.
Frequently asked questions
Does this calculator estimate MP3 or AAC file size?
No. It estimates uncompressed PCM audio. MP3 and AAC use compression, and the resulting size depends on bitrate, duration, and encoding choices. Use the encoder's settings or a format-specific estimate for those files.
Why does doubling the channel count double the result?
Each channel stores its own sample values. With duration, sample rate, and bit depth held constant, adding a second channel doubles the PCM data compared with one channel.
What is the difference between MB and MiB?
MB is decimal and equals 1,000,000 bytes. MiB is binary and equals 1,048,576 bytes. This calculator reports decimal MB, so software showing MiB may display a slightly smaller numeric value for the same file.
Will the exported file exactly match the estimate?
It may differ because the formula excludes file headers, metadata, padding, and container overhead. For a precise measurement, export the audio with the intended settings and check the resulting file's size.
Can I use the result to plan storage for a full project?
Yes, as a starting estimate for PCM audio. Add the expected number of recordings and consider backups, alternate versions, and other media files separately. The estimate does not include those additional project assets.