Video, audio and storage tool
Calculate video or audio file size from bitrate, find the video bitrate for a target file size, estimate recording time from available storage, or calculate uncompressed PCM audio.
Bitrate and file-size formulas
For compressed video or audio, file bits = (video bit/s + audio bit/s) × seconds × (1 + overhead). Divide by eight for bytes. To fit a target size, available stream bitrate = target bits ÷ seconds ÷ (1 + overhead); audio bitrate is then subtracted to obtain the video bitrate.
Recording time uses the inverse: seconds = usable storage bits ÷ total stored bit/s. The unused-storage percentage is removed before the calculation. Uncompressed PCM audio uses bitrate = sample rate × bit depth × channels.
Decimal units and binary units are not interchangeable: 1 GB = 1,000,000,000 bytes, while 1 GiB = 1,073,741,824 bytes. Bitrate is shown in decimal bits per second, as is customary for encoded media.
Checked examples
| Question | Inputs | Checked result |
|---|---|---|
| Compressed file size | 8 Mbps video + 128 kbps audio, 10 min | 609.6 MB (581.36 MiB) |
| Target video bitrate | 1 GiB, 10 min, 128 kbps audio | 14.189 Mbps video |
| Recording time | 64 GiB, 100 Mbps video + 128 kbps audio, 10% unused | 1 h 22 min 21.477 s |
| PCM audio | 48 kHz, 24-bit, stereo, 1 hour | 2.304 Mbps and 1.037 GB |
How to use the result
- Use the actual average bitrate for variable-bitrate media. A maximum or advertised bitrate can overestimate normal file size.
- Add audio to video instead of treating the video bitrate as the complete file bitrate. Container overhead is separate and format dependent.
- For a target size, leave room for audio and container overhead. The calculator rejects combinations where those consume the whole target.
- For a memory card or drive, reserving space avoids planning to fill the device completely. Manufacturers normally label storage in decimal bytes while operating systems may display binary units.
- PCM is an uncompressed estimate. WAV, RF64 or AIFF headers are small but not modeled; compressed audio requires its encoded bitrate instead.
Limits
This is an arithmetic planning tool, not a codec quality recommendation. Resolution, frame rate, chroma subsampling, bit depth, motion, noise, encoder efficiency, constant versus variable bitrate, keyframe interval and streaming-platform limits affect the bitrate needed for acceptable quality. File splitting, headers, metadata, filesystem allocation, dropped frames and recorder-specific limits are outside the model.