Estimate video size, bitrate, or time
Choose the value to solve. The chosen input stays read-only and is recalculated from the other two values.
Optional quality reference
Formula at a glance
Total bitrate = video bitrate + audio bitrate. File size in bytes = total bitrate in bits per second x duration in seconds / 8. To find the video bitrate budget, convert the target file size to bits, divide by duration, then subtract the audio bitrate. When solving recording time, the HH:MM:SS display is rounded down to the nearest second so the estimate does not exceed the target size.
Worked examples
Example: 10 Mbps video + 128 kbps audio for 10:00 is 10.128 Mbps total. 10.128 Mbps x 600 seconds / 8 = 759,600,000 bytes, or about 759.6 MB (724.4 MiB).
Unit notes
Bitrate units use decimal SI: 1 Mbps = 1,000,000 bits per second. File size units can be decimal or binary: 1 GB = 1,000,000,000 bytes, while 1 GiB = 1,073,741,824 bytes. Video tools, operating systems, and storage devices may display different unit families.
Optional quality reference
Bits per pixel per frame is a rough density reference, not a quality score. Codec efficiency and encoder settings can change visual quality at the same value. Resolution and fps do not change the file size formula unless the average bitrate changes.
Scope and export caveats
This calculator estimates data size from average bitrate and duration. It does not encode video, analyze uploaded files, or guarantee visual quality. Actual file size can change with codec, container overhead, variable bitrate, audio tracks, subtitles, metadata, and encoder settings.
After you know the file size
Use the Data Transfer Time Calculator to estimate upload or download time. For frame dimensions and crops, use the Aspect Ratio Calculator.
FAQ
How do I calculate video file size from bitrate?
Add video bitrate and audio bitrate, multiply by duration in seconds, then divide by 8 to convert bits to bytes.
How do I calculate the video bitrate needed for a target file size?
Convert the target file size to bytes, multiply by 8, divide by duration in seconds, then subtract the audio bitrate. The result is the video bitrate budget.
Should I use MB/GB or MiB/GiB?
MB and GB are decimal units based on powers of 1000. MiB and GiB are binary units based on powers of 1024. The calculator shows both so storage and software displays are easier to compare.
Does resolution or fps change the file size formula?
No. File size is driven by average total bitrate and duration. Resolution and fps are used only for the optional bits per pixel per frame reference.
Why can the real exported file be larger or smaller?
Actual exported size can change with codec, container overhead, variable bitrate, audio tracks, subtitles, metadata, and encoder settings.