Calculator Inputs
Use target size mode when storage is fixed. Use bitrate mode when encoder settings are already known.
Bitrate and Delivery Graph
The chart compares file size and per stream delivery demand across nearby video bitrate values.
Example Data Table
| Scenario | Duration | Video Bitrate | Audio Bitrate | Overhead | Estimated Size | Suggested Link |
|---|---|---|---|---|---|---|
| Mobile training clip | 00:05:00 | 900 kbps | 96 kbps | 2% | 38.10 MB | 1.30 Mbps |
| HD webinar archive | 00:45:00 | 2200 kbps | 128 kbps | 2% | 801.09 MB | 2.97 Mbps |
| Course lesson master | 01:20:00 | 3500 kbps | 160 kbps | 3% | 1,810.44 MB | 4.72 Mbps |
| Internal network preview | 00:12:00 | 1500 kbps | 128 kbps | 2% | 149.43 MB | 2.08 Mbps |
Formula Used
1) Total MP4 Bitrate
Total MP4 bitrate (kbps) = (Video bitrate + Audio bitrate) × (1 + Overhead% ÷ 100)
2) Required Video Bitrate From Target Size
Target total bitrate (kbps) = Target size (MB) × 8000 ÷ Duration (seconds)
Required video bitrate (kbps) = [Target total bitrate ÷ (1 + Overhead% ÷ 100)] − Audio bitrate
3) Estimated File Size
Estimated size (MB) = Total MP4 bitrate (kbps) × Duration (seconds) ÷ 8000
4) Recommended Network Capacity
Headroom rate (Mbps) = Total MP4 bitrate × (1 + Headroom% ÷ 100) ÷ 1000
Peak rate (Mbps) = Total MP4 bitrate × Peak factor ÷ 1000
Recommended per stream (Mbps) = Greater of headroom rate or peak rate
5) Stream Capacity On A Link
Stream capacity = Floor(Available bandwidth in Mbps ÷ Recommended per stream Mbps)
How to Use This Calculator
- Select the calculation mode.
- Enter the clip duration.
- Add audio bitrate and overhead values.
- Use target size or known video bitrate.
- Set headroom, peak factor, and stream count.
- Enter your available network bandwidth.
- Press calculate to view results above.
- Review the chart for nearby bitrate choices.
- Export the summary as CSV or PDF.
Frequently Asked Questions
1) What does MP4 bitrate mean?
MP4 bitrate is the data rate used by the audio, video, and container overhead. Higher bitrate usually improves detail, but it also increases storage and network demand.
2) Why does duration affect file size so much?
File size grows directly with duration when bitrate stays constant. Doubling the duration roughly doubles the file size, assuming the same audio, video, and overhead settings.
3) Why is audio bitrate included?
Audio consumes part of the total media budget. If your target file size is fixed, higher audio bitrate leaves less room for video bitrate.
4) What is container overhead?
Container overhead covers metadata, indexing, and packaging details inside the MP4 file. It is usually small, but it still affects total bitrate and final size.
5) Why add network headroom?
Headroom protects delivery against bursts, congestion, and routing changes. It helps reduce stalls when real network behavior becomes less stable than average conditions.
6) What does peak bitrate factor do?
Peak factor models short bursts above the average stream rate. This matters with variable bitrate content, where complex scenes can push network demand much higher.
7) Can I use this for multiple viewers?
Yes. Enter the number of concurrent streams. The calculator multiplies the recommended per stream delivery rate to estimate total link demand.
8) Is this calculator exact for every encoder?
No. It provides solid planning estimates. Actual output varies by codec settings, encoder efficiency, content complexity, scene changes, and how aggressively variable bitrate behaves.