What this Video File Size Calculator does
The Video File Size Calculator estimates how much storage a video may use based on its running time, average video bitrate, and audio bitrate. The calculation converts the combined stream bitrates into an approximate size in decimal megabytes (MB). It is useful when planning a recording, editing project, export, upload, or archive and you need a quick estimate before producing the final file.
The estimate assumes the video and audio bitrates remain constant for the entire duration. Real files can differ because of variable bitrate encoding, container metadata, subtitles, extra audio tracks, and encoder behavior. Treat the result as a planning figure rather than a guaranteed file size. The calculator does not inspect a video or encode media. It only applies the supplied values using transparent arithmetic.
Its inputs are average video bitrate in megabits per second (Mbps), audio bitrate in kilobits per second (kbps), and duration in minutes. The result is labeled Estimated file size (MB). The calculation uses decimal units, where one MB equals 1,000,000 bytes.
How to use the Video File Size Calculator
Enter the duration of the finished video, then provide its expected average video bitrate and audio bitrate. Use the settings you plan to export with, or choose reasonable estimates from your camera or editing software's documentation. If audio is not present, set the audio bitrate to zero.
- Average video bitrate describes the amount of data used for the video stream each second. Check export settings for the target resolution, frame rate, codec, and quality mode.
- Audio bitrate describes the audio stream's data rate. If a project has multiple audio tracks, this simple calculator only represents one combined audio rate, so add the track rates together when known.
- Duration is the runtime in minutes. For a clip lasting 90 seconds, enter 1.5 minutes.
For example, consider a 10-minute video averaging 8 Mbps for video with 192 kbps audio. Convert audio to megabits per second by dividing by 1,000, giving 0.192 Mbps. The combined rate is 8.192 Mbps. Multiplying by 600 seconds gives 4,915.2 megabits. Dividing by 8 converts bits to bytes, resulting in 614.4 MB. The display rounds this to 614.40 MB.
Use consistent assumptions when comparing two possible export settings. If you change the codec or quality target, the bitrate may change too, so update the bitrate input rather than expecting the calculator to infer a codec's compression efficiency.
How the Video File Size Calculator formula works
The formula combines the video and audio rates, converts both to bits per second, multiplies by the number of seconds, and then converts bits to decimal megabytes. In expression form, it is:
((video bitrate in Mbps × 1,000,000) + (audio bitrate in kbps × 1,000)) × (duration in minutes × 60) ÷ 8,000,000
Multiplying Mbps by 1,000,000 and kbps by 1,000 puts both rates in bits per second. Duration is changed from minutes to seconds. The division by eight changes bits into bytes, and the additional division by 1,000,000 expresses bytes as decimal megabytes. These unit conversions explain why the formula uses 8,000,000 in the denominator.
The formula does not include a separate container or overhead allowance. Some formats add small amounts of metadata, and actual average bitrate can vary across scenes. Motion, detail, noise, and encoder settings can all affect how much data a variable bitrate stream uses. The estimate is most useful when its bitrate inputs represent the expected average across the complete video.
Use cases for the Video File Size Calculator
Before a shoot, a production team can estimate the storage required for a planned recording duration. An editor can compare expected sizes for alternative export bitrates. A media producer preparing a delivery can estimate whether a file is likely to fit a storage limit or whether transfer time might be substantial. In each case, the result helps with planning, while the final encoded file remains the authoritative measurement.
The calculator can also help explain the effect of duration and bitrate. If the bitrates stay fixed, doubling duration doubles the estimated size. If duration stays fixed, doubling the combined bitrate also doubles the estimate. This proportional relationship is useful for rough comparisons, such as checking how a longer interview may compare with a short social clip at similar settings.
For a batch of videos, calculate representative examples rather than assuming every clip has identical size per minute. A set of clips may use different frame rates, resolutions, codecs, or quality targets. Keep notes about the settings behind each estimate so that storage planning reflects the actual workflow.
Other factors to consider when calculating video file size
Bitrate is the key input, but it is not always a fixed property of a resolution or codec. A constant bitrate export aims to hold a steady data rate. Variable bitrate encoding changes the data rate as the scene changes. A quiet static shot may need less data than fast action or a detailed scene, so average bitrate across the whole clip matters more than a brief peak.
Also consider whether the delivered file contains more than one audio stream, subtitles, chapters, or other metadata. The current estimate represents one combined audio bitrate and does not calculate those extras. If you need a conservative storage plan, allow additional room based on your own past exports and confirm the result by checking finished files.
Keep units consistent when comparing storage systems. This calculator reports decimal MB. Some operating systems display binary mebibytes (MiB), where a unit is 1,048,576 bytes, and may show a different number for the same file. Larger storage figures can also be expressed in decimal gigabytes, with 1 GB equal to 1,000 MB. The distinction is a unit convention, not a change in the underlying file.
Finally, check the export preset and actual file properties when precision matters. A file-size estimate cannot determine whether an export meets a platform's technical requirements, nor can it evaluate visual quality. Use the relevant delivery specification for those decisions and inspect a test export when available.
FAQ
How accurate is the estimated file size?
It is a bitrate-based estimate. It can be close when average bitrates and duration are known, but variable bitrate behavior, metadata, and additional streams can change the final size. Compare it with an actual export to learn how your workflow behaves.
Should I enter the maximum or average bitrate?
Use the expected average bitrate for the full video. A maximum bitrate is a peak limit and may not describe the amount of data used over the entire runtime.
What if my audio bitrate is listed in megabits per second?
Convert it to kilobits per second before entering it. Multiply the Mbps value by 1,000. For example, 0.192 Mbps corresponds to 192 kbps.
Does the result include video and audio together?
Yes. The formula adds the video bitrate and the entered audio bitrate before calculating the size. For multiple audio tracks, enter their combined bitrate as the audio value if you know it.
Why does my computer show a different size?
The calculator uses decimal MB, while some systems display binary units such as MiB. The encoded file may also include metadata or have a different average bitrate than the value used in the estimate.