Estimate video size from bitrate and duration, or solve target bitrate and recording time with audio, overhead, MB/GB, MiB/GiB, and storage breakdowns.
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Video File Size Formula
This calculator estimates encoded video file size from average bitrate and duration, or reverse-solves video bitrate or recording duration for a target size. Optional audio bitrate covers all audio tracks. Container overhead is added as a percentage of video plus audio bytes; blanks mean zero.
Size (bytes) = (video bps + audio bps) × seconds / 8 × (1 + overhead percent / 100).
Uncompressed RGB Reference
The following raw-pixel formulas and table are background comparisons, separate from the bitrate inputs above.
File size (bytes) = W × H × 3 × FPS × T
File size (GiB) = (W × H × 3 × FPS × T) / 1024³
Variable Definitions for the Uncompressed Reference
- W = video width in pixels
- H = video height in pixels
- 3 = 3 bytes per pixel for 24-bit RGB color
- FPS = frames per second
- T = total duration in seconds
For this uncompressed reference, doubling frame rate doubles raw storage and doubling both width and height quadruples it. The calculator above uses bitrate rather than pixel dimensions.
How to Calculate Video File Size
- Choose a solve mode. For file size, enter average video bitrate excluding audio.
- Enter the duration, or enter a target file size for a reverse calculation.
- Convert the full duration to seconds.
- Optionally enter combined audio bitrate and container overhead, then select Calculate.
- Read the selected answer, stream breakdown and decimal/binary sizes. Expand Calculation details for card-capacity scenarios.
Uncompressed Comparison Example
For a 1920 × 1080 video at 30 fps with a duration of 60 seconds:
GiB = (1920 × 1080 × 3 × 30 × 60) / 1024³ ≈ 10.43
So, one minute of uncompressed 1080p video at 30 fps is approximately 10.43 GiB.
General Formula for Other Bit Depths
The uncompressed reference assumes 24-bit RGB. Other raw formats use their applicable bits per pixel; these pixel dimensions and bit depths are not calculator inputs.
File size (bytes) = W × H × FPS × T × (bits per pixel) / 8
This matters when working with formats that use alpha channels, higher bit depth, chroma subsampling, or specialized camera codecs. In those cases, the actual file size can be much larger or smaller than the 24-bit RGB estimate.
Uncompressed vs. Compressed Video
The calculator above uses the average-bitrate model, which applies to encoded files when their stream bitrates are known. MP4, MOV and WebM are container formats; their contents and encoding settings determine bitrate. The formulas below omit container overhead; the calculator can add it separately.
Encoded size (bytes) ≈ total stream bitrate (bits/s) × T / 8
Encoded size (bytes) ≈ (Bᵥ + Bₐ) × T / 8
Where Bv is video bitrate and Ba is audio bitrate. This is why two videos with the same resolution and length can have very different final file sizes after export.
Quick Reference for Uncompressed 24-Bit RGB Video
| Resolution | Frame Rate | Approx. MiB / Second | Approx. GiB / Minute |
|---|---|---|---|
| 1280 × 720 | 30 fps | 79.1 | 4.63 |
| 1920 × 1080 | 30 fps | 178.0 | 10.43 |
| 1920 × 1080 | 60 fps | 356.0 | 20.86 |
| 3840 × 2160 | 30 fps | 711.9 | 41.71 |
| 3840 × 2160 | 60 fps | 1423.8 | 83.43 |
What Has the Biggest Effect on File Size?
- Resolution: More pixels increase uncompressed data; for encoded video, use the resulting average bitrate.
- Frame rate: Frame rate changes uncompressed data and can affect encoding bitrate; at fixed bitrate, the size relation is unchanged.
- Duration: Longer videos scale file size linearly.
- Color depth: More bits per pixel increases raw-frame data; the encoded estimate still depends on average bitrate.
- Compression settings: For exported files, bitrate and codec usually dominate final size.
Practical Notes
- The calculator supports decimal MB/GB and binary MiB/GiB: 1 GB = 1,000,000,000 bytes and 1 GiB = 1,073,741,824 bytes.
- Duration should be converted to seconds internally: 1 minute = 60 seconds, 1 hour = 3600 seconds.
- If a video includes an alpha channel, high bit depth, or a different pixel format, the actual uncompressed size will differ.
- Streaming and delivery formats are typically far smaller than raw RGB because they use temporal and spatial compression.
FAQ
Why is the estimated file size so large?
The uncompressed reference stores every frame directly. In the calculator, a high average bitrate or long duration produces a larger encoded-file estimate.
Why doesn’t this match my exported MP4 size?
Variable bitrate, extra audio tracks, metadata and container overhead can change exported size. Use average encoded video bitrate, combined audio bitrate and a suitable overhead assumption.
Does audio matter in this calculator?
Yes. Enter the combined bitrate of all audio tracks in the optional section. A blank audio field means no audio bytes are included.
Can I use this for 4K or 8K planning?
Yes, when you know the average encoded bitrate for the chosen 4K or 8K settings. Resolution alone is not enough to use this calculator; the raw RGB reference is a separate comparison.
