About this Video File Size
Video file size is determined by two main factors: Duration and Bitrate. Resolution (4K vs 1080p) matters only because higher resolutions typically require higher bitrates to look good. This calculator sums the video and audio streams to predict the final file size.
Who this calculator is for
- Video editors, streamers, and media teams estimating file sizes before recording or exporting.
- Anyone checking whether footage will fit on local storage or cloud transfer limits.
- Creators comparing bitrate choices against upload time and storage cost.
When to use it
- Use it to estimate how large a rendered or recorded video file will be.
- Use it when comparing bitrate presets before export or live-production capture.
- Use it before planning upload time, cloud storage, or local disk space requirements.
How to use this calculator
- Enter the Video Bitrate in Mbps.
- Enter the Audio Bitrate in Kbps (usually 128-320).
- Enter the Duration of the clip.
- The result is the estimated File Size in GB and MB.
Key assumptions
- Video bitrate is entered in Mbps and audio bitrate is entered in Kbps.
- Duration is entered in minutes and converted to seconds for the estimate.
- Negative bitrate or duration values are invalid.
Accuracy and testing
Review formula sources, default test cases, assumptions, unit handling, rounding rules, and changelog for this calculator.
How this calculator works
File Size = (Video Bitrate + Audio Bitrate) × Duration.
Since bitrates are in bits-per-second, we multiply by duration (seconds) to get total bits, then divide by 8 to get Bytes, and divide again to get Gigabytes.
Size = [(VideoMbps + AudioMbps/1000) * DurationSeconds] / 8
Inputs explained
Video Bitrate
The quality of the video stream. YouTube recommends ~8 Mbps for 1080p and ~45 Mbps for 4K.
Audio Bitrate
The quality of the sound. 192 Kbps is standard high quality; 320 Kbps is maximum for MP3/AAC.
Understanding your results
This is a raw estimate. Variable Bitrate (VBR) encoding may result in a slightly smaller file size depending on the complexity of the video scene.
Example scenarios
Streaming
10 min video. 6 Mbps video + 192 Kbps audio. Size ≈ 464 MB.
Recording
1 hour. 50 Mbps (High quality). Size ≈ 22.5 GB.
Key Features
- Combined Audio/Video logic
- Supports minutes
- GB and MB output
Tips & Best Practices
- For Twitch streaming, 6000 Kbps (6 Mbps) is the standard max bitrate.
- H.265 (HEVC) codec is more efficient than H.264, allowing lower bitrates for the same quality.
Glossary of Terms
- Bitrate
- The number of bits processed per unit of time.
- Codec
- Software used to compress or decompress digital media (e.g., H.264, VP9).