Video file size calculator
Video size is bitrate times duration. Resolution and codec only matter through the bitrate they need.
Mbit/s
kbit/s
minutes
File size
3.686GB
- File size in gibibytes
- 3.433 GiB
- Size per hour
- 3.686 GB/h
- Bitrate to hit the target size
- 8.889 Mbit/s
- Combined bitrate
- 8192 kbit/s
- Bytes
- 3 686 400 000
Show the working
- Video bitrate = 8
- Audio bitrate = 192
- Duration = 60
- Target size for the reverse = 4
- Combined bitrate = 8 * 1000 + 192 = 8192
- seconds = 60 * 60 = 3600
- bits = 8192 * 1000 * 3600 = 29 491 200 000
- Bytes = 29 491 200 000 / 8 = 3 686 400 000
- File size = 3 686 400 000 / 1e9 = 3.6864
- File size in gibibytes = 3 686 400 000 / 2^30 = 3.433 23
- Size per hour = 3.6864 / (60/60) = 3.6864
- Bitrate to hit the target size = 3600 > 0 ? 4 * 8e9 / 3600 / 1e6 : 0 = 8.888 89
Values are shown to six significant figures here; the arithmetic itself runs on exact fractions and is only rounded where a number is printed.
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The formula
- size in bits = (video + audio bitrate) x duration
- bytes = bits / 8
Variable bitrate encoders hit the target on average, not on every second, so allow a few percent of headroom.
Rough streaming bitrates: 5 Mbit/s for 1080p, 15 for 4K SDR, 25 for 4K HDR.