About this tool
Audio Bitrate & File Size Calculator — Complete Guide
What is Audio Bitrate?
Audio bitrate is the amount of data processed per second in an audio file, measured in kilobits per second (kbps). Higher bitrates mean more data is used to represent the audio, resulting in better sound quality but larger file sizes. Understanding bitrate is essential for anyone working with music production, podcast hosting, or digital audio management.
How Audio File Size is Calculated
The formula for calculating audio file size is straightforward:
File Size (MB) = (Bitrate × Duration × 60) / (8 × 1024 × 1024)
Where bitrate is in kbps and duration is in minutes. This calculator automates this math for all common audio formats, accounting for the different compression ratios of MP3, AAC, FLAC, and uncompressed WAV.
Bitrate Quality Guide
| Bitrate | Quality | Best For |
|---------|---------|----------|
| 64 kbps | Low | Voice recordings, phone calls |
| 128 kbps | Standard | Podcasts, audiobooks, casual listening |
| 192 kbps | Good | General music listening |
| 256 kbps | High | Music enthusiasts, AAC streaming |
| 320 kbps | Studio | Professional MP3, critical listening |
| 900 kbps | Lossless | FLAC archival, audiophile use |
| 1411 kbps | CD Quality | Uncompressed WAV, studio mastering |
Lossy vs Lossless Audio Formats
Lossy formats (MP3, AAC, OGG) permanently remove audio data that is deemed less audible to reduce file size. A 320 kbps MP3 is about 10× smaller than an uncompressed WAV file. Lossless formats (FLAC, ALAC) compress audio without any quality loss — the decompressed file is bit-for-bit identical to the original. FLAC files are typically 50-60% the size of WAV files.
Storage Planning by Use Case
- Smartphone (64 GB): ~12,800 songs at 128 kbps, ~5,600 songs at 320 kbps
- USB Drive (32 GB): ~6,400 songs at 128 kbps, ~2,800 songs at 320 kbps
- Podcast Episode (1 hour): ~58 MB at 128 kbps, ~144 MB at 320 kbps
- Full Album (45 min): ~41 MB at 128 kbps, ~103 MB at 320 kbps
Practical Usage Examples
Estimate a Podcast Episode Size
A podcaster wants to know how much storage a 60-minute episode needs at 128 kbps.
Duration: 60 min, Bitrate: 128 kbps → File Size: ~57.6 MBCompare Song Quality Options
A music producer wants to compare a 4-minute track at different bitrates.
Duration: 4 min → 128 kbps: 3.8 MB | 320 kbps: 9.6 MB | FLAC: 27 MB | WAV: 42.3 MBStep-by-Step Instructions
Step 1: Enter Duration. Type the audio length in minutes. For a 3-minute song, enter "3". For a 1-hour podcast, enter "60".
Step 2: Select Bitrate. Choose the audio quality level. 320 kbps is studio-grade MP3, 128 kbps is good for speech, and 1411 kbps is uncompressed CD quality.
Step 3: View Results. Click "Calculate" to see the estimated file size in MB, plus a comparison table showing all common formats.
Step 4: Plan Storage. Use the storage guide to estimate how many tracks fit on your device at different quality levels.
Step 5: Copy Results. Copy the comparison table for your project planning, podcast production, or music library management.
Core Benefits
Multi-Format Support: Calculate sizes for MP3, AAC, WAV, FLAC, and OGG formats simultaneously — compare lossless vs lossy in one click.
Podcast Production Planning: Estimate episode file sizes before recording to plan hosting bandwidth and RSS feed storage.
Music Library Management: Calculate how many songs fit on your phone, USB drive, or cloud storage at different quality levels.
Streaming Bandwidth Estimation: Determine bandwidth requirements for streaming audio at various bitrates.
Instant Accuracy: All calculations run locally in your browser — no upload needed, no waiting, no server dependency.
Frequently Asked Questions
Multiply the bitrate (in kbps) by the duration (in seconds), then divide by 8 to convert bits to bytes. For example: 320 kbps × 210 seconds (3.5 min) = 67,200 kilobits = 8,400 KB ≈ 8.2 MB.
320 kbps captures about 2.5× more audio data per second than 128 kbps. The difference is most noticeable in complex music (orchestral, jazz) and high-frequency sounds like cymbals. For speech and podcasts, 128 kbps is usually sufficient.
At 128 kbps (assuming 4-minute songs): ~3.8 GB. At 320 kbps: ~9.6 GB. At FLAC lossless: ~27 GB. At uncompressed WAV: ~42 GB.
For casual listening on earbuds or speakers, 128 kbps is acceptable. However, audiophiles and anyone using high-quality headphones will notice compression artifacts. 192 kbps or 256 kbps AAC is the sweet spot for most listeners.
Spotify uses 96 kbps (Low), 160 kbps (Normal), and 320 kbps (Very High) for its Premium tier. Apple Music streams at 256 kbps AAC. YouTube Music uses 256 kbps AAC for premium subscribers.
Both are lossless and sound identical. FLAC compresses audio to about 50-60% of WAV size without quality loss. WAV is uncompressed and works universally. FLAC is better for storage; WAV is better for compatibility with older equipment.
A 1-hour podcast at 128 kbps mono is approximately 57.6 MB. At 64 kbps (voice-optimized), it drops to about 28.8 MB. Most podcast hosting platforms recommend 128 kbps for stereo or 64 kbps for mono speech.
Yes, up to the limits of the codec. For MP3, quality improvements plateau above 320 kbps. For AAC, 256 kbps is considered transparent quality. Beyond that, you need lossless formats (FLAC, WAV) for measurable improvement.
Among common formats: Opus at 64 kbps offers excellent quality in the smallest file size. For more standard formats, 128 kbps AAC provides good quality at about 1 MB per minute of audio.
At 128 kbps: ~57 MB per hour. At 320 kbps: ~144 MB per hour. At CD quality (1411 kbps): ~634 MB per hour. For mobile data planning, 128 kbps streaming uses about 1 GB per 17.5 hours.