Video File Size Calculator
Enter duration, video bitrate, audio bitrate, and target MB to estimate file size or find the bitrate budget before compression.
The calculator uses bitrate and time, so treat the result as a planning estimate before you run the browser compressor.
Video file size calculator
Estimated file size
27.8 MB
Video bitrate for target
1.07 Mbps
Use this video file size calculator to estimate MB from bitrate and duration, then choose a compression target. Real output can vary by codec, motion, and browser encoder.
For a target MB, the calculator subtracts audio bitrate first and shows the remaining video bitrate budget.
What this video file size calculator helps you decide
Use a video file size calculator before compression when you need a realistic target instead of guessing a percentage.
Estimate MB from bitrate
The video file size calculator combines video bitrate, audio bitrate, and duration to estimate the final MB.
Bitrate to MB
Reverse-plan a target size
Type a target MB and the video file size calculator shows the approximate video bitrate budget left after audio.
Target bitrate
Move straight to compression
After the video file size calculator gives you a practical target, use the compressor below to test that target on your MP4.
Calculate then compress
How to use the video file size calculator
A video file size calculator is useful when duration and bitrate matter more than a generic compression percentage.
Enter the real duration
Start the video file size calculator with the clip length in minutes. Duration has a direct impact on output size.
Add video and audio bitrate
Use the bitrate shown by your editor or media inspector. The video file size calculator adds video and audio bitrate before estimating MB.
Set the target MB
Type the file-size limit you need for email, chat, review, or storage. The video file size calculator shows the approximate video bitrate you can afford.
Compress and compare
Use the calculated target in the compressor, then compare the actual output because codecs, motion, and browser encoding can change the result.
Compress after you choose a target size
Use the calculator result as a starting point, then choose an MP4 and set the same target MB in the compressor.
The calculator uses bitrate and time, so treat the result as a planning estimate before you run the browser compressor.
Compress video
The video compressor creates a new MP4 download.
Pick the approximate maximum size you want. Compress by percentage or MB; the two fields stay linked.
Video file size calculator assumptions
It is an estimate, not a promise
A video file size calculator works from bitrate and time. Actual MP4 output can vary with codec efficiency, scene complexity, keyframes, and audio settings.
Variable bitrate can move the result
If your encoder uses variable bitrate, simple video file size calculator math may not match the final file exactly. Leave a buffer below the upload limit.
Tiny targets reduce quality
When the required video bitrate looks very low, use the video file size calculator as a warning: trim the clip, lower resolution, or use a quality-first compressor target.
Video File Size Calculator FAQ
Use the estimate in a compression workflow
After the video file size calculator, continue with the main compressor, the quality-first page, or the beginner guide.
CompressMP4
Use a free online video compressor for MP4 files. Set a percentage or target MB and download a smaller MP4 without uploading video.
Compress Video Without Losing Quality
Compress video without losing quality with a gentler MP4 preset. Keep files local, compare size, and use the largest target that still fits.
Make Video File Smaller
make video file smaller for sharing, upload, or storage. Start from 55%, compress locally, and download a smaller MP4.