How do you calculate MP3 or AAC file size?

Multiply duration by bitrate and divide by 8 to convert bits to bytes. Sample rate, channels, and bit depth affect quality, but bitrate is what mainly determines the final size for compressed exports.

How do you calculate WAV size?

Multiply duration by sample rate, bit depth, and channel count, then divide bit depth by 8 to convert to bytes per sample.

No. FLAC is lossless but compresses by different amounts depending on the source, so the result is an estimate rather than a fixed final size.

Estimate Before You Convert

Audio File Size Calculator

Estimate audio file size for MP3, AAC, Opus, WAV, and FLAC using duration, bitrate, sample rate, bit depth, and channels.

Useful for upload limits, email attachments, and storage planning
Switch between compressed and lossless estimates
Runs instantly in the browser with no file upload needed

Use the calculator

Estimate your output size

Use this calculator before converting audio so you can choose a bitrate or lossless format that fits your upload, storage, or sharing target.

Format type

Quick presets

Hours Minutes Seconds Bitrate (kbps)

Compressed formats are estimated from bitrate and duration. Sample rate, channels, and bit depth affect quality decisions, but once bitrate is fixed they do not materially change this size estimate. Container overhead is small, so the real file usually lands close to this range.

Estimated size

Projected output

Live estimate

9.16 MB

approx.

8.74 MiB | 9,160,000 bytes

10 minutes of MP3 at 128 kbps.

Per minute

0.92 MB

Per hour

54.93 MB

Formula used

size = duration x bitrate / 8

Need to hit a form limit? Use the estimate here, then open Audio Bitrate Converter or Compress Audio Files to generate a smaller file that matches the target.

How audio file size is calculated

Compressed audio: size is driven mostly by bitrate and duration. A 128 kbps file uses roughly twice the space of a 64 kbps file at the same duration.
WAV / PCM: size depends on sample rate, bit depth, channels, and duration.
FLAC: start from WAV size, then estimate the compression ratio. Speech usually compresses more than dense music.

Quick reference by common targets

Use case	Suggested format	Typical target
Voice notes and meetings	MP3 or AAC	64-96 kbps mono
Podcast uploads	MP3	96-128 kbps mono or stereo
Music sharing	MP3 or AAC	192 kbps stereo
Editing masters	WAV	44.1 kHz, 16-bit, stereo or higher

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Need to actually make the file smaller?

Estimate the target size here, then use the converter to export an MP3, AAC, WAV, or FLAC version that fits your workflow.

Open Audio Bitrate Converter

Audio File Size Calculator

Estimate your output size

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How audio file size is calculated

Quick reference by common targets

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