Audio File Size Calculator — MP3, AAC, FLAC & WAV
An audio file size calculator converts bitrate and duration into the megabytes a track, album or podcast will occupy — for planning libraries, uploads and phone storage.
Quick answer: Size (MB) = kbps × seconds ÷ 8,000. A 3.5-minute track is about 3.4 MB at 128 kbps, 6.7 MB at 256 kbps and 8.4 MB at 320 kbps; the same track as FLAC is about 23 MB and as uncompressed WAV about 37 MB.
Formats: 90m · 1h30m · 5400s · plain number = seconds
| Duration | Size (decimal GB/MB) |
|---|---|
| 1 min | 1.92 MB |
| 5 min | 9.6 MB |
| 30 min | 57.6 MB |
| 1 h | 115.2 MB |
| 2 h | 230.4 MB |
| 10 h | 1.152 GB |
| Per minute | 128 kbps → 0.96 MB · 256 kbps → 1.92 MB · 320 kbps → 2.4 MB |
|---|---|
| Per hour | 128 kbps → 57.6 MB · 320 kbps → 144 MB · FLAC → ~405 MB |
| CD audio (WAV 16-bit 44.1 kHz) | 1,411 kbps → ~10.6 MB per minute |
| Streaming tiers | Spotify: 96 / 160 / 320 kbps depending on quality setting |
Lossy quality versus size
Modern AAC and Opus reach transparency — where trained listeners cannot reliably tell the difference — around 160–256 kbps for stereo music, so 320 kbps buys peace of mind more than audible quality. Dropping from 320 to 128 kbps saves 60% of storage; whether that matters depends more on your headphones and listening environment than on the file itself.
Lossless costs real space
FLAC typically lands at 50–60% of the uncompressed size (about 900 kbps for CD-quality stereo), while WAV stores every sample raw at 1,411 kbps. A 100-album collection is roughly 55 GB in FLAC or 30 GB in 320 kbps MP3 — and phone storage makes the trade-off sharply visible. Podcasts are the opposite case: 96 kbps mono is plenty for speech and keeps an hour at about 43 MB.
Recording and voice work
For spoken-word recording, WAV at 44.1 or 48 kHz is the safe master format; convert to 96–128 kbps mono for delivery. Video editors should note that 48 kHz is the video standard — recording at 44.1 and resampling later costs a generation of quality for no storage benefit worth having.
When to use this calculator
- Estimating how many albums fit on a phone or SD card.
- Choosing a podcast export bitrate that fits an RSS size budget.
- Comparing FLAC versus MP3 libraries before a drive purchase.
- Sizing a voice-recording session in WAV before recording.
- Checking upload size for a music demo or audiobook platform.