Audio Bitrate Calculator
Work out exactly how large an audio file will be at any bitrate, duration, sample rate, channel count and bit depth.
Convert with this tool
Files stay on your device. There is no upload, no queue and no watermark, so a conversion works even with the network switched off after the page has loaded.
Supported formats & processing
| Input | Numbers you type — nothing is calculated until you change a value |
|---|---|
| Output | A live result table, recalculated on every keystroke |
| Processing | Plain arithmetic in this tab — instantaneous and offline |
About this tool
Knowing the file size before you encode saves a lot of trial and error, especially when a platform imposes a limit. The arithmetic is straightforward but easy to get wrong: uncompressed size is sample rate multiplied by channel count multiplied by bit depth, divided by eight for bytes, multiplied by the duration in seconds.
This calculator shows the uncompressed figure and then the same duration at five standard MP3 bitrates plus a FLAC estimate, so you can compare the trade directly. The compression-versus-PCM row makes the cost of lossless storage explicit.
Features
- Uncompressed PCM size for any rate, channel count and bit depth
- MP3 sizes at 64, 128, 192, 256 and 320 kbps
- A FLAC estimate based on typical 55 percent compression
- Direct comparison between lossless and lossy storage
- Duration entered as minutes and seconds
- Seven sample rates from 8 kHz to 96 kHz
Frequently asked questions
How do I calculate audio file size myself?
Sample rate × channels × (bit depth ÷ 8) × duration in seconds gives the byte count for uncompressed audio. For a compressed format, bitrate in bits per second × duration in seconds ÷ 8 gives the size.
Why is FLAC not a fixed size?
FLAC is lossless compression, so the ratio depends on the content. Silence compresses far better than dense music. The 55 percent figure used here is a reasonable average for typical material.
How large is a 320 kbps MP3 per minute?
About 2.4 MB. That is 320,000 bits per second × 60 seconds ÷ 8 bits per byte, which is 2,400,000 bytes.
Does 24-bit audio really double the size?
Compared with 16-bit it adds 50 percent, not 100 — the bit depth goes from 16 to 24 bits per sample, which is a factor of 1.5. Going to 32-bit float doubles it relative to 16-bit.