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A two-hour movie has no fixed file size. As a practical estimate, each 1 Mbps of average total bitrate works out to about 0.9 decimal GB over two hours: at 2 Mbps, expect about 1.8 GB; at 5 Mbps, 4.5 GB; at 10 Mbps, 9 GB; and at 20 Mbps, 18 GB. These are calculated estimates, not guaranteed sizes for a particular movie.
Estimate a two-hour movie’s file size
For a 7,200-second movie, multiply its average total bitrate in megabits per second (Mbps) by 0.9 to estimate the file size in decimal gigabytes (GB). “Total” matters: if the bitrate is for video alone, the audio bitrate must be added separately. Container data, subtitles, and other tracks can add a little more.
| Average total bitrate | Estimated size for two hours |
|---|---|
| 2 Mbps | About 1.8 GB |
| 5 Mbps | About 4.5 GB |
| 10 Mbps | About 9 GB |
| 20 Mbps | About 18 GB |
These estimates use decimal GB, where 1 GB is 1,000,000,000 bytes. A device or operating system that displays storage in binary units may show a different number, and the actual file can vary because of variable bitrate and extra tracks.
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- Find the movie’s average total bitrate in Mbps. If you have separate video and audio rates, add them together first.
- Multiply the bitrate by 7,200 seconds, the runtime of a two-hour movie.
- Divide by 8 to convert bits to bytes, then divide by 1,000,000,000 to convert bytes to decimal GB.
For example, a file averaging 5 Mbps overall is approximately 5 × 7,200 ÷ 8 ÷ 1,000,000,000 = 4.5 GB. Average bitrate is more useful than a peak or momentary reading because many videos use variable bitrate: the amount of data changes during playback as scenes demand more or less detail.
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Why resolution does not determine file size
A 1080p or 4K label describes resolution, not a unique bitrate or storage requirement. The codec and encoder, frame rate, HDR or color depth, motion, scene complexity, and desired image quality all affect how much data an encode uses. Apple’s HLS authoring guidance calls its bitrate recommendations initial targets and says they should be evaluated for the particular content and workflow. The IETF’s RFC 9317 likewise identifies factors including resolution, frame rate, color depth, codec, encoding parameters, scene complexity, and motion.
Apple’s example video bitrates
Apple lists example video encoding targets of 6 Mbps for 1080p H.264, 4.5 Mbps for 1080p HEVC, and 11.6 Mbps for 4K HEVC. Applied to two hours, those video-only rates imply about 5.4 GB, 4.05 GB, and 10.44 GB respectively, before audio not included in the video rate and container overhead. These examples illustrate how codec and resolution can affect an encode; they are not predictions for a specific commercial movie download.
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Streaming speed is not download size
Netflix recommends a stable internet connection of at least 3 Mbps for 720p playback, 5 Mbps for 1080p, and 15 Mbps for 4K. Those figures describe recommended connection speeds, not the average bitrate or file size of a downloaded movie. Streaming services may adjust the delivered bitrate, so a playback-speed recommendation cannot tell you exactly how large a download will be. Similarly, YouTube’s 35–45 Mbps recommendation for standard-frame-rate 2160p uploads concerns source encodes uploaded to YouTube, not typical streaming or download files.
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Check what the bitrate number includes
A media file can contain separate video and audio tracks, subtitles, and other data. Apple’s AVFoundation reference defines averageVideoBitrate as the average bitrate of a video track, or of combined content when the track is muxed. Check whether a bitrate figure refers to video alone or the whole file before applying the estimate. If it is video-only, add the audio rate; allow for additional tracks and container data as well.
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