Estimated bytes = (video bits/s + audio bits/s) × seconds ÷ 8 × allowance factorHow to use this calculator
- Choose file-size estimation or a video bitrate for a target size limit.
- Enter duration, average video bitrate or size budget, combined audio bitrate and any optional allowance.
- Review decimal MB, binary MiB and the ideal upload-time estimate. Confirm an actual encoded file before delivery.
Worked example
An illustrative 60-second clip at 8 Mbps video plus 192 kbps audio contains 61.44 MB of encoded payload before extra allowance. That is 58.59375 MiB. At a constant 20 Mbps upload rate, transferring that payload alone would take 24.576 seconds, excluding network and processing overhead.
Average bitrate determines the estimate
Use average or target bitrate, not a peak value. Resolution, frame rate, codec, content and encoder settings affect the bitrate needed for a chosen quality, but they do not independently determine file size. The tool does not claim a particular bitrate will produce an acceptable image.
MB, MiB, Mbps and kbps
MB and GB use decimal byte counts; MiB and GiB use binary byte counts. A bit is not a byte: eight bits make one byte. Video bitrate here uses decimal megabits per second, and combined audio uses decimal kilobits per second. Changing the unit selector preserves the quantity entered.
A size budget is not an encoder
The reverse calculation reserves space for audio and the allowance before working out the remaining video bitrate. It does not compress a file or guarantee an upload limit will be met. Variable bitrate, container metadata and additional tracks can change the actual result; check the exported file.
Reference: YouTube: bitrate and encoding settings.
Common questions
Can I calculate video size from resolution alone?
No. Two videos with the same resolution and duration can have different bitrates and file sizes. Use a measured average bitrate or an export setting as the input, and treat a target-bitrate calculation as a planning estimate.
Does audio bitrate mean per channel?
Enter the total bitrate of all encoded audio tracks. A stereo track’s stated bitrate commonly describes that complete encoded track, not a separate bitrate to multiply by two. Check the actual export settings rather than assuming a channel multiplier.
How much overhead should I add?
The default is zero, meaning no extra allowance is assumed. If you add an allowance, it is a planning input you choose, not a measured MP4 container overhead or a guaranteed safety margin. A real file includes more than idealized encoded payload.
Is the upload-time estimate a speed test?
No. It divides estimated file bits by the upload speed you enter. It assumes constant throughput and excludes protocol overhead, retries, connection variation and destination processing. Clear the optional upload-speed field to omit it.