Audio File Size Calculator
Estimate an audio file's size from its duration and format — uncompressed WAV/PCM (sample rate, bit depth, channels) or compressed MP3/AAC/OGG/FLAC at a given bitrate — with a byte/KB/MB/GB breakdown.
Input
Output
Binary units (1 KB = 1024 bytes) — matches how Windows/macOS file managers display file sizes.
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Guides
What does this calculator do?
Enter a duration and pick an audio format to get an instant estimate of the resulting file size, broken down in bytes, KB, MB and GB. It covers both uncompressed and compressed audio:
- Uncompressed WAV/PCM — size is exact and depends on sample rate, bit depth and channel count:
bytes = sampleRate × (bitDepth ÷ 8) × channels × durationSeconds. A 1-minute CD-quality (44,100 Hz, 16-bit, stereo) WAV file is 10,584,000 bytes — about 10.09 MB. - Compressed MP3, AAC or OGG Vorbis — size depends only on the chosen bitrate:
bytes = bitrateKbps × 1000 ÷ 8 × durationSeconds. A 30-minute podcast at 128 kbps comes out to roughly 27.47 MB. - FLAC (lossless) — FLAC's compression ratio depends on the actual audio content, so there's no exact formula. This tool estimates it as a percentage (30-70%, default 60%) of the equivalent WAV size, which is the typical real-world range for FLAC.
How to use it
- Enter the duration as hours, minutes and seconds.
- Choose an audio format. For MP3/AAC/OGG, pick a bitrate. For WAV/FLAC, pick sample rate, bit depth and channels (mono or stereo).
- The estimated size and a full breakdown table update automatically as you change any field.
- Copy the headline size or download the breakdown table as CSV.
Which KB/MB/GB does this use?
This tool uses binary units: 1 KB = 1,024 bytes, 1 MB = 1,024 KB, 1 GB = 1,024 MB. That's the same convention Windows Explorer, macOS Finder and most file managers use when they show you a file's size — so the numbers here should match what you'd actually see on disk. It is not the decimal SI convention (1 KB = 1,000 bytes) that some networking and storage-marketing contexts use, which would show slightly smaller numbers for the same file. The exact byte count is always shown in the breakdown table if you need it for downstream math.
FAQ
Why is my real file a different size than the estimate? Encoders add container/metadata overhead (ID3 tags, WAV/RIFF headers), and variable-bitrate (VBR) encoding — common for MP3 and AAC — doesn't hold a constant bitrate throughout, so real files vary somewhat from a constant-bitrate estimate.
Why doesn't FLAC have an exact formula like WAV? FLAC is lossless but content-adaptive: quieter or repetitive audio compresses more, dense or noisy audio compresses less. 50-70% of the source WAV size is the typical range, hence the adjustable slider rather than a fixed number.
Can I use this for podcast or audiobook planning? Yes — set the duration to your episode or chapter length and the bitrate you plan to publish at (128 kbps MP3 is a common podcast default) to estimate storage and download size per episode.
Privacy
All calculations run entirely in your browser (or via the API if you call it programmatically) — no audio file is uploaded or required, since the estimate is based purely on duration and format settings.