Audio File Size Comparison: MP3, WAV, FLAC, OGG, AAC

File size is one of the most practical factors in choosing an audio format. Whether you are emailing a file, uploading to Discord, streaming from a website, or filling a storage drive, the numbers matter. This guide gives you concrete sizes — not vague descriptions — across the major formats.

The Reference: A 4-Minute Song

All examples below use a 4-minute stereo audio track as the reference. This is a typical pop, rock, or electronic song length. Sizes are approximate and vary slightly depending on the specific encoder, the musical content (complex content compresses slightly less efficiently), and encoder settings.

File Size Table: 4 Minutes of Stereo Audio

| Format | Bitrate / Settings | Approximate Size | |--------|-------------------|------------------| | WAV | 16-bit, 44.1 kHz | ~40 MB | | WAV | 24-bit, 48 kHz | ~82 MB | | FLAC | 16-bit, 44.1 kHz | ~22 MB | | MP3 | 320 kbps | ~9.2 MB | | AAC | 256 kbps | ~7.5 MB | | MP3 | 192 kbps | ~5.5 MB | | OGG Vorbis | 192 kbps | ~5.5 MB | | MP3 | 128 kbps | ~3.7 MB | | Opus | 128 kbps | ~3.8 MB | | Opus | 96 kbps | ~2.8 MB | | Opus | 64 kbps | ~1.9 MB |

The Math Behind Bitrate and File Size

For compressed formats (MP3, AAC, OGG, Opus), the calculation is straightforward:

File size in MB = (Bitrate in kbps x Duration in seconds) / 8 / 1000

Let's check MP3 at 192 kbps for 4 minutes (240 seconds):

192 x 240 / 8 / 1000 = 5.76 MB

That matches the table. The formula works for any constant-bitrate (CBR) encoding. Variable bitrate (VBR) encoding, which most modern encoders use by default, will hover around a target and produce slightly different results depending on the audio content.

For WAV, the calculation is different — there is no bitrate setting because nothing is compressed:

File size in MB = Sample rate x Bit depth x Channels x Duration / 8 / 1,000,000

For stereo 16-bit 44.1 kHz WAV, 4 minutes (240 seconds):

44100 x 16 x 2 x 240 / 8 / 1,000,000 = 42.3 MB

For 24-bit 48 kHz stereo WAV:

48000 x 24 x 2 x 240 / 8 / 1,000,000 = 82.9 MB

FLAC sits between WAV and compressed formats. It achieves lossless compression of approximately 40–60% compared to WAV, depending on the complexity of the audio content.

Format Comparison by Use Case and Size

Archiving: FLAC at ~22 MB per song

FLAC is the archival sweet spot. It is half the size of WAV, completely lossless, and widely supported on modern platforms. A 500 GB drive holds approximately 22,700 FLAC songs vs approximately 12,500 WAV files.

Everyday Listening: MP3 or AAC at 192–256 kbps

At 192 kbps, MP3 and OGG produce files around 5.5 MB per song — about one-eighth the size of WAV with quality that is transparent for most listeners in most environments. A 1 GB phone storage allocation holds approximately 180 songs at this bitrate.

Maximum Compression: Opus at 64–96 kbps

Opus at 96 kbps delivers approximately 2.8 MB per 4-minute track with quality comparable to MP3 at 192 kbps. For podcast delivery or speech content where bandwidth costs matter, Opus is significantly more efficient than any other widely supported format.

Real-World Constraints

Email Attachments

Most email providers cap attachments at 25 MB. At that limit:

• You can send one WAV track (barely, if it is under 4 minutes at 16-bit/44.1kHz)
• You can send three MP3s at 320 kbps
• You can send four to five MP3s at 192 kbps
• You can send six to seven Opus files at 96 kbps

For emailing audio, convert to MP3 at 192–256 kbps before attaching. Convert WAV to MP3 in AudioUtils to get an email-ready file immediately.

Discord and Messaging Apps

Discord's free tier allows 25 MB per upload. A 4-minute WAV at 16-bit/44.1kHz is roughly 40 MB — over the limit. An MP3 at 192 kbps is 5.5 MB — comfortably under.

Web Streaming

Streaming a WAV file requires a 1.4 Mbps connection just to stream without buffering. At 192 kbps MP3, a 100 kbps connection is sufficient. Opus at 96 kbps streams reliably even on poor mobile connections.

Cloud Storage

If you are storing thousands of tracks in cloud storage and paying per gigabyte, format choice has a direct cost impact. A 10,000-track library:

• As WAV 16-bit/44.1kHz: ~400 GB
• As FLAC: ~220 GB
• As MP3 320 kbps: ~92 GB
• As MP3 192 kbps: ~55 GB

How to Reduce Audio File Size with AudioUtils

All conversions run locally in your browser:

• To shrink a WAV: convert WAV to MP3 and choose 192 kbps for a good size-to-quality balance
• To shrink a FLAC: convert FLAC to MP3 with the same settings
• To shrink an M4A: convert M4A to MP3 — helpful for iTunes files that are already reasonably sized but need broader compatibility

Your files never leave your device. The conversion happens in WebAssembly in your browser, and the output downloads directly to your computer.

Summary

File size is not just a storage concern — it affects what you can email, share, stream, and store. WAV gives you maximum quality at maximum size. Opus gives you minimum size with surprisingly high quality. MP3 and AAC sit in the middle where compatibility meets efficiency. FLAC is the lossless sweet spot between WAV and the lossy formats. Choose based on what your files need to do, not just how they sound.