Audio File Size Calculator

Estimate audio file size from duration and bitrate, or calculate uncompressed PCM storage from sample rate, bit depth, and channel count.

What Is an Audio File Size Calculator?

An audio file size calculator estimates how much storage an audio recording or export will require.

The required calculation depends on whether the audio is compressed or stored as uncompressed PCM.

For compressed formats such as MP3, AAC, and Opus, file size is primarily estimated from:

• Duration
• Average bitrate

For uncompressed PCM formats such as WAV and AIFF, file size is calculated from:

• Duration
• Sample rate
• Bit depth
• Number of channels

This calculator supports both methods. It can be used for podcasts, music production, voice recordings, video soundtracks, audiobooks, field recordings, streaming media, and archive planning.

All calculations run locally in your browser. No audio file is selected, analyzed, or uploaded.

How to Use the Audio File Size Calculator

Select the audio type

Choose one of the following modes:

• Compressed audio
• Uncompressed PCM audio

Select Compressed for formats and codecs such as MP3, AAC, or Opus when you know the average bitrate.

Select Uncompressed PCM for WAV or AIFF audio when you know the sample rate, bit depth, and channel count.

A WAV or AIFF container can hold different kinds of audio. The PCM mode is intended for uncompressed linear PCM data rather than every possible file that uses one of these containers.

Enter the duration

Enter the complete audio duration using hours, minutes, and seconds.

For a 90-minute podcast, enter:

Hours: 1
Minutes: 30
Seconds: 0

For a 45-second sound effect, enter:

Hours: 0
Minutes: 0
Seconds: 45

Enter the compressed audio bitrate

In compressed mode, enter the average bitrate in kilobits per second.

Examples include:

• 64 kbps
• 96 kbps
• 128 kbps
• 192 kbps
• 256 kbps
• 320 kbps

If the audio uses variable bitrate, enter the expected average bitrate.

Enter the PCM settings

In uncompressed PCM mode, select:

• Sample rate
• Bit depth
• Channel count

For example:

Sample rate: 48 kHz
Bit depth: 24-bit
Channels: Stereo

Select Calculate file size to display the estimated storage, decimal MB, binary MiB, data rate, and storage required per minute.

Compressed Audio File Size Formula

For compressed audio, file size is calculated from the average bitrate and duration.

The bitrate is entered in kilobits per second:

1 kbps = 1,000 bits per second

The basic formula is:

File size in bits
= Bitrate in kbps × 1,000 × Duration in seconds

Because eight bits equal one byte:

File size in bytes
= Bitrate in kbps × 1,000 × Duration in seconds ÷ 8

To convert bytes into decimal megabytes:

File size in MB
= File size in bytes ÷ 1,000,000

This formula estimates the encoded audio data. Tags, embedded artwork, chapters, container information, and other metadata may increase the final size.

Example: One Hour of 320 kbps Audio

Consider a one-hour compressed audio file encoded at 320 kbps.

Convert one hour into seconds:

1 hour = 3,600 seconds

Calculate the total number of bits:

320 × 1,000 × 3,600
= 1,152,000,000 bits

Convert bits into bytes:

1,152,000,000 ÷ 8
= 144,000,000 bytes

Convert bytes into decimal megabytes:

144,000,000 ÷ 1,000,000
= 144 MB

The estimated file size is:

144 MB

The same number of bytes is approximately:

137.33 MiB

The amount of storage used per minute is:

2.4 MB per minute

Estimated Compressed Audio Size per Hour

The following values show the approximate storage required for one hour of compressed audio at a constant or average bitrate.

The actual result may differ when using variable bitrate, embedded cover artwork, chapters, metadata, or container-specific data.

Uncompressed PCM File Size Formula

Uncompressed PCM storage is calculated differently because there is no compressed bitrate setting.

The raw data rate depends on:

Sample rate × Bit depth × Channel count

The PCM bitrate formula is:

PCM bitrate in bits per second
= Sample rate × Bit depth × Channels

The file size formula is:

File size in bytes
= Sample rate × Bit depth × Channels × Duration ÷ 8

For example, 48 kHz, 24-bit stereo audio has:

48,000 samples per second
× 24 bits per sample
× 2 channels
= 2,304,000 bits per second

The corresponding data rate is:

2,304 kbps

This is much higher than a compressed 320 kbps audio stream.

Example: One Hour of 48 kHz, 24-Bit Stereo PCM

Use the following settings:

Duration: 1 hour
Sample rate: 48,000 Hz
Bit depth: 24-bit
Channels: 2

Calculate the PCM bitrate:

48,000 × 24 × 2
= 2,304,000 bits per second

Multiply by the duration:

2,304,000 × 3,600
= 8,294,400,000 bits

Convert bits into bytes:

8,294,400,000 ÷ 8
= 1,036,800,000 bytes

The estimated size is:

1,036.8 MB

This equals:

1.0368 GB

The binary value is approximately:

988.77 MiB

The calculation excludes the WAV or AIFF header and any additional metadata.

Estimated PCM Storage per Hour

Increasing the sample rate, bit depth, or channel count increases the uncompressed data rate and storage requirement.

Compressed Audio vs. Uncompressed PCM

Compressed and uncompressed audio serve different purposes.

Compressed audio

Compressed formats reduce storage requirements by representing the audio more efficiently.

Common examples include:

• MP3
• AAC
• Opus
• Vorbis

Some compressed formats are lossy, meaning that information is removed to achieve a smaller file. The audible result depends on the codec, bitrate, encoder, source material, and listening conditions.

Compressed audio is commonly used for:

• Streaming
• Podcasts
• Web delivery
• Mobile listening
• Video soundtracks
• Downloads
• Email attachments

Uncompressed PCM

Uncompressed PCM stores sample values directly without perceptual compression.

PCM is commonly used inside formats such as WAV and AIFF.

It is useful for:

• Recording
• Editing
• Mixing
• Sound design
• Intermediate files
• Audio analysis
• Professional production
• Archival workflows

Uncompressed PCM files are much larger than typical compressed delivery files.

Constant Bitrate vs. Variable Bitrate Audio

Constant bitrate

Constant bitrate, or CBR, attempts to use the same number of bits for every second of audio.

A 128 kbps CBR file uses approximately 128,000 bits per second throughout the recording.

This makes file size straightforward to estimate:

File size = Bitrate × Duration

Small differences may still occur because of headers, tags, padding, or container data.

Variable bitrate

Variable bitrate, or VBR, changes the bitrate according to the complexity of the audio.

A simple passage may use less data, while a complex musical passage may use more.

For VBR audio, enter the expected average bitrate rather than a temporary peak or maximum value.

If the achieved average bitrate is different from the value entered, the final file size will also be different.

Quality-based export modes may not provide a predictable average bitrate in advance. A short test export can provide a more realistic estimate for similar material.

How Audio Bitrate Affects File Size

Bitrate represents the amount of compressed audio data used per second.

For files of equal duration:

• Doubling the bitrate approximately doubles the audio data size
• Halving the bitrate approximately halves the audio data size
• Increasing duration increases file size in direct proportion
• Reducing duration reduces file size in direct proportion

For example, one hour at 128 kbps requires approximately 57.6 MB. One hour at 256 kbps requires approximately 115.2 MB.

The second file uses twice the bitrate and therefore requires approximately twice the storage.

A higher bitrate can preserve more audio information, but it does not guarantee that every listener will hear an improvement. Results also depend on the codec, encoder, source quality, playback equipment, and listening environment.

How Sample Rate Affects PCM File Size

Sample rate describes how many samples are stored per second for each audio channel.

Examples include:

• 44.1 kHz = 44,100 samples per second
• 48 kHz = 48,000 samples per second
• 96 kHz = 96,000 samples per second
• 192 kHz = 192,000 samples per second

For uncompressed PCM, doubling the sample rate doubles the raw audio data rate when bit depth and channel count remain unchanged.

For example, 96 kHz PCM requires twice the sample data of 48 kHz PCM with the same bit depth, channel count, and duration.

For compressed audio, sample rate does not directly determine file size when the average encoded bitrate is already known. A 128 kbps compressed file uses approximately the same amount of encoded audio data per second regardless of the source sample rate.

How Bit Depth Affects PCM File Size

Bit depth describes the number of bits used to represent each PCM sample.

Common settings include:

• 16-bit
• 24-bit
• 32-bit

For uncompressed PCM, file size increases directly with bit depth.

A 24-bit PCM file requires 1.5 times as much raw sample storage as a 16-bit PCM file with the same sample rate, channel count, and duration.

24 ÷ 16 = 1.5

A 32-bit PCM file requires twice the raw sample storage of a 16-bit file:

32 ÷ 16 = 2

Bit depth can affect available dynamic range and production flexibility, but the appropriate setting depends on the recording, editing, delivery, and compatibility requirements.

How Channel Count Affects File Size

Each channel contains a separate sequence of audio samples.

Common channel configurations include:

• Mono: 1 channel
• Stereo: 2 channels
• 5.1 surround: 6 channels
• 7.1 surround: 8 channels

For uncompressed PCM, stereo requires twice as much sample data as mono when all other settings remain the same.

A six-channel PCM file requires three times as much raw audio storage as a stereo file:

6 channels ÷ 2 channels = 3

For compressed audio, the channel count can affect the bitrate needed for a particular quality level. However, when the final average bitrate is known, the bitrate already determines the estimated encoded size.

MP3 File Size Calculation

An MP3 file’s approximate size can be calculated from its average bitrate and duration.

For a 60-minute MP3 at 128 kbps:

128 × 1,000 × 3,600 ÷ 8
= 57,600,000 bytes
= 57.6 MB

For the same duration at 320 kbps:

320 × 1,000 × 3,600 ÷ 8
= 144,000,000 bytes
= 144 MB

ID3 tags and embedded cover artwork can increase the finished file size.

A high-resolution cover image may be significant in a very short audio file, even though it represents a small percentage of a long recording.

WAV File Size Calculation

For uncompressed PCM WAV audio, use the PCM mode.

The primary storage requirement comes from:

Sample rate × Bit depth × Channels × Duration

A WAV file also contains a header and may contain metadata or additional chunks. These elements are not included in the raw PCM estimate.

Not every WAV file contains uncompressed PCM. WAV is a container and can hold other audio encodings. If a WAV file uses a compressed codec, calculate it from the encoded average bitrate instead of applying the uncompressed PCM formula.

AAC and Opus File Size Calculation

AAC and Opus are compressed audio codecs. Their file sizes can be estimated from average bitrate and duration.

For example, one hour at 96 kbps is approximately:

96 × 1,000 × 3,600 ÷ 8
= 43.2 MB

Two codecs using the same average bitrate and duration will produce approximately the same amount of encoded audio data.

The difference is not the mathematical file size formula. The difference is the quality, compatibility, latency, encoder behavior, and features each codec provides at that bitrate.

Why the Actual File Size May Be Different

The calculator provides an estimate rather than a guaranteed final byte count.

Differences can be caused by:

Metadata

Audio files may include artist names, album information, dates, comments, loudness information, and other tags.

Embedded artwork

Album covers and podcast artwork are stored as additional image data.

Container overhead

Formats contain headers, indexes, timing information, and other structural data.

Variable bitrate

The achieved average bitrate may differ from the expected value.

Encoder delay and padding

Some codecs add samples or frames to support encoding and decoding behavior.

Chapters and transcripts

Podcast and audiobook files may contain chapter information, synchronized text, or other supplementary data.

Floating-point audio

A 32-bit floating-point format may have storage or container behavior that differs from a simple integer PCM workflow.

Multiple streams

A container may include more than one audio stream or additional data tracks.

For strict capacity limits, leave additional storage and confirm the result with a test export.

MB vs. MiB

The calculator displays both decimal megabytes and binary mebibytes.

A decimal megabyte is:

1 MB = 1,000,000 bytes

A binary mebibyte is:

1 MiB = 1,048,576 bytes

The same file therefore has a lower numerical value in MiB than in MB.

For example:

144,000,000 bytes = 144 MB
144,000,000 bytes ≈ 137.33 MiB

OutputMath displays both units to avoid confusion between decimal storage specifications and binary measurements.

Planning Podcast Storage

Podcast production commonly involves more storage than the final published episode alone.

A project may contain:

• Original recordings
• Separate microphone tracks
• Remote guest recordings
• Music and sound effects
• Edited sessions
• Lossless masters
• Compressed delivery files
• Transcripts
• Cover artwork
• Backup copies

For example, a one-hour 128 kbps delivery file is approximately 57.6 MB. However, separate 48 kHz, 24-bit mono recordings for several speakers can require much more storage.

If four participants are recorded to four independent mono PCM tracks:

48,000 × 24 × 4
= 4,608,000 bits per second

For one hour, the raw sample data is approximately:

2,073.6 MB

Storage planning should therefore include the complete production workflow rather than only the final MP3 or AAC file.

Planning Music Production Storage

Music projects may include dozens or hundreds of recorded tracks, alternate takes, rendered effects, frozen instruments, samples, and backups.

To estimate multitrack PCM storage, treat each separate mono track as one channel.

For example, 24 mono tracks recorded at 48 kHz and 24-bit have a combined raw data rate of:

48,000 × 24 × 24
= 27,648,000 bits per second

One hour of continuous audio at that combined data rate would require approximately:

12,441.6 MB

Actual project requirements depend on how long each track contains recorded material and how the digital audio workstation stores edits, takes, caches, and project history.

Audio File Size vs. Video File Size

Audio and video file sizes use the same basic relationship between bitrate and duration.

For compressed media:

File size = Bitrate × Duration

Video bitrates are usually much higher than compressed audio bitrates, so video commonly accounts for most of a finished video file.

Use the Video File Size Calculator when a file contains video and audio.

Use the Video Bitrate Calculator when you have a target video file size and need to calculate the available video bitrate.

Related Calculators

Video File Size Calculator — Estimate video storage from duration and video and audio bitrates.

Video Bitrate Calculator — Calculate the video bitrate required for a target file size and duration.

DPI/PPI Calculator — Calculate image resolution, PPI, and print dimensions.

Aspect Ratio Calculator — Simplify aspect ratios and calculate matching dimensions.

Frequently Asked Questions

How large is one hour of MP3 audio?

The result depends on bitrate.

Examples include:

• 128 kbps: approximately 57.6 MB
• 192 kbps: approximately 86.4 MB
• 256 kbps: approximately 115.2 MB
• 320 kbps: approximately 144 MB

Metadata and embedded artwork may increase the final size.

How large is one hour of WAV audio?

It depends on sample rate, bit depth, and channel count.

One hour of 44.1 kHz, 16-bit stereo PCM is approximately 635.04 MB. One hour of 48 kHz, 24-bit stereo PCM is approximately 1,036.8 MB.

Is WAV always uncompressed?

No. WAV is a container and can hold different audio formats. The PCM mode applies to uncompressed PCM audio stored in a WAV or similar container.

Does a higher sample rate increase MP3 size?

Not directly when the final average MP3 bitrate remains unchanged. A 128 kbps compressed file is estimated from 128 kbps and duration.

For uncompressed PCM, increasing the sample rate directly increases file size.

Does stereo double the file size?

For uncompressed PCM, stereo contains two channels and requires twice the raw sample storage of mono with the same sample rate, bit depth, and duration.

For compressed audio, use the final average bitrate because the codec determines how data is allocated between channels.

What bitrate should I enter for VBR audio?

Enter the expected or measured average bitrate. Do not use a brief peak or maximum value as though it were maintained throughout the file.

Does the calculation include album artwork?

No. Embedded images, tags, metadata, chapters, and other overhead are not included.

Can I calculate an audiobook’s storage requirement?

Yes. Enter the full duration and expected compressed bitrate. Long audiobook projects may be easier to calculate using the total duration of all chapters.

Are my recordings uploaded?

No. The calculation uses only the values entered into the form and runs locally in your browser.

Calculation Methodology

OutputMath calculates compressed audio size using:

File size in bytes
= Average bitrate in kbps × 1,000 × Duration in seconds ÷ 8

Uncompressed PCM size is calculated using:

File size in bytes
= Sample rate × Bit depth × Channels × Duration in seconds ÷ 8

The calculator uses:

1 byte = 8 bits
1 kbps = 1,000 bits per second
1 MB = 1,000,000 bytes
1 MiB = 1,048,576 bytes

The result excludes headers, tags, embedded artwork, metadata, chapters, encoder padding, additional streams, and other overhead.

For compressed VBR audio, accuracy depends on the difference between the entered bitrate and the bitrate actually achieved by the encoder.

For critical storage planning, allow additional capacity and verify the estimate with a representative test recording or export.

Learn More About Audio File Size

Want to compare storage requirements for MP3, AAC, WAV, and FLAC? Read our guide to audio file size by bitrate, format, and duration for formulas, practical estimates, and recording examples.

Learn how bitrate, duration, sample rate, bit depth, and channels affect storage in our guide to calculating audio file size.