Video File Size & Bitrate

When to use it

Use this before exporting a clip with a file-size limit. The example is a simulated 120-second video with 20 Mbps video, 192 kbps total audio, a 500 MB limit and a 5% reserve. It estimates one export; duplicate the canvas to compare delivery versions.

Inputs

Calculation method

Total rate = video bitrate + audio bitrate. Payload = total rate × duration. Headroom = limit × (1 − reserve) − payload. Video bitrate budget = limit × (1 − reserve) ÷ duration − audio bitrate. The canvas converts bits to bytes through real quantities: 1 Mbps = 1,000,000 bit/s, 1 kbps = 1,000 bit/s, 1 MB = 1,000,000 bytes. The final budget is expressed in Mbps by dividing by the 1 Mbps basis.

20 [Video bitrate Mbps] × 1 Mbps + 192 [Total audio bitrate kbps] × 1 kbps → Total rate MB/s

Total rate MB/s × 120 [Duration s] → Payload MB

500 [Size limit MB] × (1-5 [Reserve]%)-Payload MB → Headroom MB

(Size limit MB × (1-Reserve%)/Duration s-Total audio bitrate kbps × 1 kbps)/1 Mbps → Video bitrate budget Mbps

Change one input

Change duration from 120 to 180 seconds. The payload increases and headroom shrinks; the bitrate budget falls. Current video bitrate is an independent input and is not automatically replaced by the calculated budget.

Results are displayed to at most two decimal places; later formulas use unrounded values.

Scope and limits

• Simulated values; MB is decimal, not MiB.
• Average bitrate estimates payload, not exact encoded file size.
• The reserve is a chosen allowance, not a platform rule.

Duration and size limit must be positive; bitrates nonnegative; reserve from 0% inclusive to 100% exclusive. A nonpositive video budget leaves no allowance for positive video bitrate. Negative headroom means the planned reserve is not met. Container overhead and variable bitrate can change actual size; inspect the exported file. Display rounding does not guarantee a safe encoder setting.

Download and import into Calvance to edit the numbers. The canvas does not reject every invalid input; check the stated ranges.

Common questions

Is the budget a quality recommendation?

No. It is a size constraint, not a VBR maximum or a quality target. Resolution, motion and codec still matter. Vimeo’s storage guidance explains bitrate-based estimation.

What if the video has no audio?

Set total audio bitrate to zero. For multiple tracks, enter their combined average bitrate.

How to import your template

We recommend using the latest version of Calvance.

1. Save the file. Choose Download template and save the .calvx file to Files on your iPhone or iPad. From a computer, you can send it to your device with AirDrop.
2. Open Import. In All Canvases in Calvance, tap the add button to open the template screen, then choose Import.
3. Choose the file. Select the saved .calvx file to create your own canvas. Importing uses one canvas from your allowance.
4. Edit and check. Check the results against the worked example, then add your numbers. Duplicate the canvas to keep different versions.

Download .calvx file