Video file size calculator
A video file's size is duration times bitrate, nothing more. Resolution and codec matter only because they decide what bitrate the picture needs to look good.
The calculation uses decimal gigabytes, the way memory cards and storage services report them. Variable bitrate encoding drifts from the target, and the container adds roughly one percent on top of the stream.
Frequently asked questions
What bitrate does 1080p need?
Between 8 and 12 Mbps with H.264 for ordinary material, and 15–20 for fast motion. H.265 and AV1 reach the same quality at roughly half.
Why is the file bigger than the calculation?
Because variable bitrate overshoots the target on complex scenes, and the container adds metadata, indexes and extra tracks.
Does bitrate or resolution matter more?
Bitrate. 4K at an insufficient bitrate looks worse than 1080p at a fitting one, because compression artefacts are more visible than missing resolution.