Video Bitrate & File Size Calculator
Estimate how large a video file will be from its bitrate and length, or work out the bitrate needed to hit a target file size.
Solve for
Video bitrate unit
kbps
min
s
- 1
Duration in seconds
10 × 60 + 0 = 600 - 2
Total bitrate (video + audio)
5,000,000 + 128,000 = 5,128,000 - 3
File size in bytes
5,128,000 × 600 ÷ 8 = 384,600,000Divide by 8 to convert bits to bytes. - 4
File size in MB
384,600,000 ÷ 1,000,000 = 384.6
How does this calculator work?
Video file size equals total bitrate (video plus audio, in bits per second) times duration in seconds, divided by 8. Convert kbps by 1,000 and Mbps by 1,000,000, then divide bytes by 1,000,000 for MB or 1,000,000,000 for GB. Reverse it to find the bitrate that fits a target size.
Formula
How this is calculated
Bitrate is the number of bits used per second of media. This tool first converts each bitrate to bits per second: kbps × 1,000 and Mbps × 1,000,000. The video and audio bitrates are summed into a total bitrate, and the audio field is treated as kbps (set it to 0 for a video-only stream). Duration is taken as minutes × 60 + seconds.
In "file size" mode the size in bytes equals total_bps × duration_s ÷ 8 (eight bits per byte). That byte count is shown in both MB (÷ 1,000,000) and GB (÷ 1,000,000,000), using decimal SI units as encoders and storage labels typically do. In "required bitrate" mode the calculation is inverted: total_bps = size_bytes × 8 ÷ duration_s, and the audio bitrate is subtracted to reveal the video bitrate budget.
The estimate assumes constant bitrate (CBR); variable-bitrate (VBR) encodes will vary around this figure, and container/muxing overhead is ignored, so real files are usually slightly larger. Duration must be greater than zero. If the requested target size is so small that audio alone overflows it, the implied video bitrate goes negative and a warning is shown.
Frequently asked questions
This calculator uses decimal units: 1 MB = 1,000,000 bytes and 1 GB = 1,000,000,000 bytes, matching how bitrates (kbps/Mbps) and most storage marketing are defined. Operating systems that report MiB/GiB (powers of 1,024) will show a slightly smaller number for the same file.
Estimates assume constant bitrate and ignore container overhead, subtitles, and metadata. VBR encoding lets the bitrate rise and fall with scene complexity, so the final size can differ by a few percent in either direction.
Switch to "Required bitrate" mode, enter your target size and the clip duration, and the tool returns the total bitrate you can afford. Subtract your audio bitrate to get the video bitrate to set in your encoder.
Also known as
TG we-Calculate Editorial Team. (2026). Video Bitrate & File Size Calculator [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/video-bitrate-calculator
TG we-Calculate Editorial Team. "Video Bitrate & File Size Calculator." TG we-Calculate. 2026. https://we-calculate.com/calculator/video-bitrate-calculator.
TG we-Calculate Editorial Team, "Video Bitrate & File Size Calculator," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/video-bitrate-calculator
@misc{wecalculate_video_bitrate_calculator, title = {Video Bitrate & File Size Calculator}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/video-bitrate-calculator}}, year = {2026}, note = {TG we-Calculate} }
Did this calculator help you?