video file size calculator
work out how big a video file will be from its bitrate and length.
the file size formula
every video's size comes from two numbers
file size = (video + audio bitrate) × length ÷ 8
bitrate is bits per second; file size is bytes, and a byte is 8 bits. 8 Mbps for one second is 1 MB.
file size per minute
at youtube's recommended bitrates, video only
| quality | per minute |
|---|---|
| 720p | 37.5 MB |
| 1080p | 60.0 MB |
| 1080p at 60 fps | 90.0 MB |
| 1440p | 120 MB |
| 4K | 338 MB |
file size per hour
at youtube's recommended bitrates, video only
| quality | per hour |
|---|---|
| 720p | 2.25 GB |
| 1080p | 3.60 GB |
| 1080p at 60 fps | 5.40 GB |
| 1440p | 7.20 GB |
| 4K | 20.25 GB |
video file size questions
the answers people look for most
file size = bitrate × length ÷ 8. bitrate is in bits per second and file sizes are in bytes, hence the 8. a 10-minute video at 8 Mbps with 128 kbps audio is (8,128,000 × 600) ÷ 8 bytes, which is 610 MB.
at youtube's recommended 8 Mbps for 1080p, plus 128 kbps audio, about 3.66 GB. the same video at 60 fps (12 Mbps) is about 5.46 GB.
windows explorer counts a megabyte as 1,048,576 bytes but still calls it "MB", while macOS and drive makers count 1,000,000. the same 3.66 GB file shows as 3.41 GB in windows. nothing is missing.
only through the bitrate. at a fixed bitrate, size depends on length alone, whatever the resolution. higher resolutions need a higher bitrate to look good, which is why they end up bigger. encoders set to a quality target instead of a bitrate vary the bitrate with the content, so their file sizes are estimates.
at youtube's recommended 45 Mbps for 4K at 30 fps, about 338 MB per minute before audio.
record long sessions without huge files
tau records your screen or camera as a timelapse, capturing one frame every few seconds instead of 30 a second, so hours of work stay small.
more: bitrate calculator · timelapse file size estimator · all tools