Video File Size Calculator
Exact file size from video length and bitrate.
What it does
Video size is bitrate times duration: every second stores megabits per second, and eight bits make each byte. Resolution, frame rate, and codec pick the bitrate; multiplication does the rest.
The tool above takes minutes with total Mbps. It returns megabytes with gigabytes beside them, plus minutes per gigabyte for planning cards and uploads.
The default 10 minutes at 8 Mbps holds 600 MB (0.6 GB), about 16.7 minutes per gigabyte. An hour at 12 Mbps runs 5.4 GB by the same single multiplication.
The decimal math follows NIST SI prefixes with FCC broadband guides measuring consumer bitrates the same way. Real files add audio tracks and container headers around the video stream.
How to use
- Enter the video length in minutes.
- Enter the total bitrate in Mbps including audio.
- Read megabytes first for cards and drives.
- Use gigabytes for uploads and archives.
- Add margin for audio and headers before publishing.
Formula
- 8
- Bits per byte bridging rates and files.
- 1000
- Decimal MB per GB used here.
- Mbps
- Video plus audio megabits per second.
Variable bitrate averages into the entered number; spikes need headroom above the mean. Decimal gigabytes match drives and hosts; editing bins showing GiB read about 7% smaller.
Worked example
Example: 10 minutes at 8 Mbps
Length 10 min, bitrate 8 Mbps.
- Seconds: 10 x 60 = 600 s.
- Megabits: 8 x 600 = 4800 Mb.
- Megabytes: 4800 / 8 = 600 MB = 0.6 GB.
- Per GB: 8000 / 8 / 60 = 16.7 min.
- Tool shows 600 MB, 0.6 GB, 16.7 min/GB.
Reference table
| Bitrate | File | Minutes/GB |
|---|---|---|
| 5 Mbps | 2.25 GB | 26.7 min |
| 8 Mbps | 3.6 GB | 16.7 min |
| 12 Mbps | 5.4 GB | 11.1 min |
| 25 Mbps | 11.25 GB | 5.3 min |
Limits
- Mean bitrate assumed; VBR spikes need headroom.
- Audio and subtitles add beyond video math.
- Containers add headers around streams.
- Streaming ladders re-encode at several rates.
Common mistakes
- Dividing by 8 twice (bits to bytes once).
- Mixing decimal GB with binary GiB bins.
- Forgetting audio beside video bitrate.
- Trusting nominal rates without measuring exports.
- Planning cards to the last megabyte.
Try it yourself
Quick checks. Answers sit tucked under each question.
60 minutes at 12 Mbps?
12 x 3600 / 8 = 5400 MB = 5.4 GB.
Minutes per GB at 5 Mbps?
8000 / 5 / 60 = 26.7 min.
30 minutes at 25 Mbps?
25 x 1800 / 8 = 5625 MB = 5.63 GB.
Questions
How big is 10 minutes at 8 Mbps?
600 MB (0.6 GB): 8 x 600 seconds over 8.
What bitrate for 1080p?
Often 8 to 12 Mbps uploaded; platforms re-encode lower.
Why bigger than math?
Audio tracks, subtitles, thumbnails, and container headers add up.
GB or GiB?
This page uses decimal GB (1000 MB) like drives and hosts.
Does codec matter?
For quality at a size, yes. For size math, only the bitrate number counts.
How do I shrink files?
Lower bitrate, shorter length, or newer codecs at equal quality.