File size = bitrate × duration ÷ 8. An 8 Mbps video with 192 Kbps audio running one hour is (8,000,000 + 192,000) × 3,600 ÷ 8 = 3.69 GB. Enter your own numbers below; it also works as a bitrate calculator in reverse using the table.
Formula
Bytes = (video bitrate + audio bitrate in bits per second) × seconds ÷ 8. Divide by 1,000,000 for MB or 1,000,000,000 for GB. Containers add a small overhead, usually around 1–2%, so real files can be slightly larger.
Size per minute and per hour by bitrate
| Total bitrate | Per minute | Per hour |
|---|---|---|
| 1 Mbps | 8 MB | 0.45 GB |
| 2.5 Mbps | 19 MB | 1.12 GB |
| 5 Mbps | 38 MB | 2.25 GB |
| 8 Mbps | 60 MB | 3.60 GB |
| 16 Mbps | 120 MB | 7.20 GB |
| 35 Mbps | 262 MB | 15.75 GB |
| 45 Mbps | 338 MB | 20.25 GB |
Rows are exact for the stated bitrate (decimal MB/GB). Which bitrate your camera or stream uses depends on the codec and settings, so check its spec sheet.
Bitrate from a file size
Reverse it: bitrate (Mbps) = size in MB × 8 ÷ seconds. A 700 MB file of 90 minutes is 700 × 8 ÷ 5,400 = 1.04 Mbps.
Related: Kbps to Mbps, upload time calculator, GiB to GB, byte to MB converter.
FAQ
How do I calculate video file size?
Multiply total bitrate (bits per second) by duration in seconds, then divide by 8 to get bytes.
How big is a 1 hour video at 8 Mbps?
8,000,000 × 3,600 ÷ 8 = 3,600,000,000 bytes, which is 3.6 GB before audio and overhead.
How do I calculate bitrate from file size?
Bitrate in Mbps = file size in MB × 8 ÷ duration in seconds.
Why is my file bigger than the calculator says?
Variable bitrate encoding, extra audio tracks, subtitles and container overhead all add bytes.
Is this in GB or GiB?
The main result is decimal GB (10^9 bytes); the GiB figure is shown too.