Video File Size & Bitrate Calculator

Enter the running time as hours, minutes, and seconds, then the video bitrate your encoder is configured for. For a one-hour export at 10 Mbps with 192 kbps AAC audio and 2% container overhead:

Total bitrate = 10,000 + 192 = 10,192 kbps, or 10.192 Mbps. Raw stream bits = 10,192 × 1,000 × 3,600 = 36,691,200,000. Adding 2% container overhead gives 37,425,024,000 bits, and dividing by 8 gives 4,678,128,000 bytes.

That is 4,678.13 MB, 4.678 GB in the decimal units encoders and drive manufacturers use, and 4.357 GiB in the binary units your operating system reports. All three describe the identical file. The audio track contributes about 88 MB of that total (small, but not nothing over an hour).

The bar chart on this page recalculates the same duration across a range of bitrates, which makes the proportionality obvious: file size tracks bitrate exactly, so halving the bitrate halves the file.

Target-size mode inverts the formula, which is what you actually need when a platform imposes a hard ceiling. Say you have a 90-minute film to fit inside a 25 GB limit, with a 256 kbps audio track and 2% container overhead.

Total bitrate budget = 25 GB × 8,000,000,000 bits ÷ 1.02 ÷ 5,400 seconds ÷ 1,000 = 36,310.8 kbps. Subtract the 256 kbps reserved for audio and the video bitrate that lands on the target is 36,054.8 kbps, or 36.05 Mbps.

Feed 36.05 Mbps back into size mode with the same duration and audio and you get 25 GB back, which is the check worth doing whenever a delivery spec and an encoder disagree. Note how generous that budget is: 36 Mbps is well above streaming bitrates, so a 25 GB ceiling on a 90-minute film is not a real constraint at 1080p. Halve the duration to 45 minutes and the same 25 GB allows roughly twice the bitrate.

A gigabyte has two meanings. Encoders, storage vendors, and this calculator's GB figure use the decimal definition: 1 GB = 1,000,000,000 bytes. Windows and most file browsers use the binary definition (1,073,741,824 bytes) while still writing the label "GB". The binary unit holds 7.4% more bytes, so the same file reads about 7% smaller when measured that way: the 4,678,128,000-byte export above is 4.678 GB decimal and 4.357 GiB binary.

This is not rounding error, and neither number is wrong. It is why a "32 GB" memory card shows as roughly 29.8 GB when you insert it, and why an export that a spec sheet says fits a 25 GB limit can be rejected by a system measuring in binary units. This calculator returns both so you can check against whichever definition the receiving system uses.

The other reason a real file differs from the estimate is variable bitrate. Most modern encoders vary bitrate scene by scene and target an average rather than holding a constant rate, so the number you configure is a target the encoder aims at, not a guarantee. Constant-bitrate encoding matches this arithmetic almost exactly; variable-bitrate output typically lands within a few percent of it, and constant-quality modes (CRF and similar) can miss it by a wide margin because they do not target a bitrate at all.

Once you know what a single file costs, the data storage calculator scales it into a whole library, and the bandwidth calculator converts the same bitrate into the connection speed needed to stream it live rather than store it.

This calculator performs exact arithmetic on the bitrate, duration, audio rate, and overhead you enter. It cannot tell you what bitrate your footage actually needs. That depends on resolution, frame rate, codec efficiency, and how much motion and detail the content contains. A static interview at 1080p looks fine at a bitrate that would make an action sequence at the same resolution fall apart.

It assumes a fixed average bitrate across the whole clip. Variable-bitrate and constant-quality encoding modes will land near this figure but not on it, and two-pass encodes that target a file size directly will be closer than single-pass constant-quality ones. Container overhead is modelled as a flat percentage, whereas real overhead varies with the container format, keyframe interval, chapter and subtitle tracks, and embedded metadata or thumbnails.

Newer codecs change the picture entirely and are outside the arithmetic: H.265 and AV1 typically deliver comparable quality to H.264 at roughly half the bitrate, so the right input for the same footage differs by codec. Still pictures have the same generational gap, since AVIF is the image format built on AV1, and Compress Image saves one photo as JPG, WebP or AVIF so the sizes can be compared side by side. And nothing here accounts for multiple audio tracks, subtitle streams, or the extra copies a workflow generates: proxies, intermediate renders, and backups often outweigh the master file in total storage.

The Data Storage Calculator turns a per-file size into a whole photo and video library in GB or TB, which is the natural next step once you have sized one export. The Bandwidth Calculator converts the same bitrate figure into the connection speed required to stream rather than store, including concurrent viewers. The Download Time Calculator tells you how long a file of this size takes to transfer at a given speed, and the Screen Resolution & PPI Calculator covers the pixel density of the display you are capturing or delivering for. And if you are weighing a different codec or archive format, the Compression Ratio Calculator converts between compression ratio and space saved, and prices the storage and transfer time the difference actually buys.