Video File Size Calculator
Estimating Output Size Before You Export
A rendered video's file size is dictated almost entirely by two things: how many bits per second the encoder is asked to spend (the bitrate) and how long the footage runs. Knowing the resulting size ahead of an export saves you from filling a drive with an oversized file, or from finding out an upload limit was exceeded only after the export finished.
The Formula
Bitrate is measured in kilobits per second, but file size is conventionally reported in megabytes, so the formula multiplies the combined kbps figure by the duration in seconds to get total kilobits, then divides by 8,192 (8 bits per byte × 1,024 kilobytes per megabyte) to convert to megabytes.
Worked Examples
| Video bitrate | Audio bitrate | Duration | Resulting size |
|---|---|---|---|
| 8,000 kbps | 128 kbps | 10 min | 595.31 MB |
| 8,000 kbps | 192 kbps | 90 min | 5,400 MB (≈5.27 GB) |
A 90-minute feature encoded at a typical 1080p streaming bitrate lands around 5–6 GB — roughly consistent with common downloadable 1080p release sizes.
Where This Matters
- Planning an upload — platforms and email attachments often cap file size, so estimating the export size in advance tells you whether you need to lower the bitrate or split the file.
- Budgeting storage on a project drive — before rendering a long project, knowing the expected output size helps confirm there's enough free space.
- Comparing codec efficiency — running the same duration at different target bitrates shows the size trade-off before committing to an export setting.
How to Use This Calculator
- Enter the Video Bitrate in kbps.
- Enter the Audio Bitrate in kbps (optional — leave blank to treat as zero).
- Enter the Duration in minutes.
- Select Calculate to see the estimated file size in MB.
Related Calculations
Not sure what bitrate to enter? Check recommended values with the Stream Bitrate Calculator, or size out storage for a full recording schedule with the Video Storage Requirement Calculator.