Predict a video's file size before you export. Enter duration and bitrate, or pick a quality preset, and get the size in MB and GB. Includes a reverse mode: set a target size to find the bitrate. Free.
Estimate size
Enter duration and bitrate, or start from a preset.
MB
Result
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The math
File size is just bitrate × duration ÷ 8. A 10-minute video at 8 Mbps video plus 0.192 Mbps audio is 8.192 × 600 ÷ 8 ≈ 614 MB. Container overhead adds a percent or two, which the estimate ignores.
Bitrate, not resolution, decides size: a 4K video at 8 Mbps is the same size as 1080p at 8 Mbps, just lower quality per pixel.
Reverse mode
Have a hard limit, like a 100 MB upload cap or a messaging app restriction? Switch to reverse mode, enter the target size and duration, and the tool tells you the maximum video bitrate that fits.
Presets reflect typical YouTube recommendations; adjust to taste for your platform.
Multiply the total bitrate (video plus audio, in megabits per second) by the duration in seconds, then divide by 8 to convert megabits to megabytes.
Does resolution affect file size?
Only indirectly. Size is set by bitrate and duration. Resolution matters for quality: the same bitrate spread over more pixels (4K) looks worse per pixel than over fewer (1080p).
What bitrate should I use for YouTube 1080p?
YouTube recommends 8 Mbps for standard 1080p and up to 12 Mbps for high-motion content. The presets include common platform recommendations as starting points.
How do I fit a video under 100 MB?
Use reverse mode: enter 100 MB and your duration, and it computes the maximum bitrate. Lowering duration or accepting lower quality are the only other levers.
Why is my exported file bigger than estimated?
Container overhead, variable-bitrate spikes on complex scenes, and thumbnails or metadata add a few percent. Two-pass encoding lands closest to the estimate.