Media File Size Calculations

These calculations will help you to estimate the size of audio files.

Notes

1. "X" means "multiplied by". Forward slash (/) means "divided by".
2. Kbps means "Kilobits per second" (1,000 bits per second). KB means KiloBytes (1,000 Bytes). There are 8 bits in a byte. Note the uppercase "B" for bytes in "KB". A lowercase "b" (Kb) would indicate bits.
3. Calculations for MP3 files generally include both left and right stereo channels. Calculations for PCM files must be multiplied by 2 to allow for both left and right stereo channels.
4. We took reasonable care in computing these figures, but you may want to double-check them if you're working on an important project. We did a casual experiment with a one-minute PCM file, and Windows Explorer reported it to be slightly smaller (10,337 KB) than what was predicted by the calculations below (10,584 KB). This may be due to differences between binary and decimal counting systems (multiples of 2 versus multiples of 10). In addition, file header information and ID3 tags (for MP3s) will have an effect on the numbers. In general, however, we have have found the figures below to be useful for approximating audio file sizes.

MP3 File Size Calculations

Formula: Kbps = bits per second / 8 = Bytes per second x 60 seconds = Bytes per minute x 60 minutes = Bytes per hour