Calculator
Example Data Table
| Duration | Video Bitrate | Audio Bitrate | Estimated Size |
|---|---|---|---|
| 00:05:00 | 2,500 kbps | 128 kbps | 106.58 MB |
| 00:15:00 | 5,000 kbps | 160 kbps | 627.81 MB |
| 01:00:00 | 20,000 kbps | 256 kbps | 10.24 GB |
Formula Used
The core relationship is: Size(bytes) = Duration(seconds) × TotalBitrate(bits/second) ÷ 8
- TotalBitrate = VideoBitrate + (AudioBitrate × AudioTracks)
- We convert kbps to bits/second using kbps × 1000
- We apply overhead and safety multipliers: × (1 + Overhead%) × (1 + Safety%)
How to Use This Calculator
- Enter the video duration in hours, minutes, and seconds.
- Pick a preset, then press Apply preset if desired.
- Set video bitrate, audio bitrate, and the number of audio tracks.
- Adjust container overhead and safety margin for more realistic sizing.
- Click Calculate to see results below the header.
- Use Download CSV or Download PDF for your records.
Duration-to-Size Relationship
Video files scale almost linearly with time when bitrate is stable. A 10‑minute clip encoded at 5,000 kbps video plus 160 kbps audio carries 5,160 kbps total, or about 387 MB of payload before overhead. If you store in common decimal units, that becomes roughly 418 MB after 3% container overhead and 5% safety headroom. Longer timelines amplify small bitrate changes, so lock the duration first.
Bitrate Selection by Use Case
Bitrate depends on resolution, motion, and codec efficiency. For typical web delivery, 720p H.264 often lands near 2,500 kbps video, while 1080p H.264 may target 5,000 kbps. Newer encoders can cut that by 30–40% for similar visual quality. Audio is usually 96–192 kbps for stereo; multi‑language releases multiply the audio budget by track count. For 4K workflows, start at 15–25 Mbps video, test short segments, then tune downward until motion and gradients remain clean under scrutiny.
Overhead and Safety Margins
Real files are not pure media payload. Containers add headers, timestamps, and metadata, and variable bitrate peaks may exceed your average setting. The overhead setting models those bytes, while the safety margin reserves extra capacity for complex scenes, subtitles, or muxing differences. For strict platform limits, raise safety to 8–12%. For controlled archives, 3–6% is often sufficient.
Storage and Transfer Planning
Storage planning is easier when you convert sizes into copies and transfer time. Two backups plus a working copy means three total copies; a 2.3 GB master becomes about 6.9 GB reserved. Upload time is roughly size ÷ link rate: a 1 GB file over 20 Mbps needs around 6–8 minutes in ideal conditions. If your connection is shared, plan with a lower effective Mbps.
Workflow Tips for Predictable Outputs
To hit predictable sizes, prefer constant rate or capped two‑pass encoding, then verify the output against your target. Keep audio consistent across episodes, and document preset choices so teams reproduce results. When a platform enforces a maximum size, switch to “max bitrate from target size” mode, set your duration, and treat the suggested bitrate as a ceiling, not a promise.
Does the estimate include audio and multiple tracks?
Yes. The total bitrate adds video plus audio bitrate multiplied by the number of audio tracks. Set audio to zero if you only want video payload sizing.
Why is the final file sometimes larger than the estimate?
Encoders may use variable bitrate, add extra metadata, or package subtitles differently. Increase the safety margin and overhead percentage when you need tighter guarantees against size drift.
Which units should I choose: decimal or binary?
Choose decimal for marketing and most cloud storage billing. Choose binary to match many operating system file dialogs. The calculator shows both when you download reports.
What overhead percentage is reasonable?
For MP4 or MKV, 2–4% is typical. Add more when you include multiple audio tracks, chapters, or subtitles. For strict distribution limits, pair 3–4% overhead with extra safety.
How do I use target size mode for a platform limit?
Select “Max bitrate from target size,” enter duration and the limit, then keep your encoder’s average bitrate at or below the suggested maximum. Treat it as a ceiling and retest after exporting.
How reliable is the upload time estimate?
It assumes steady throughput with no congestion and uses Mbps as megabits per second. Real transfers vary with Wi‑Fi, routing, and server speed, so plan with a lower effective rate for busy networks.