BITRATE AND STORAGE
How to Estimate Video File Size
Video file size is driven mainly by total bitrate and duration, with container overhead adding a smaller amount.
SHORT ANSWER
Start with the inputs you can verify
Video file size is driven mainly by total bitrate and duration, with container overhead adding a smaller amount.
What the estimate means
Add video and audio bitrates before multiplying by duration.
Convert bits to bytes and use the correct decimal or binary storage units when comparing results.
Where estimates go wrong
Variable bitrate makes an estimate approximate; the measured average bitrate determines the final size.
Keep the source measurements and assumptions with the result so another person can review or update the estimate later.
A practical workflow
- Record programme duration and expected video and audio bitrates.
- Calculate total bits, convert to bytes, and label the unit convention.
- Add headroom for variable bitrate, alternate tracks, captions, and container overhead.