Video File Size Calculator

Estimate video file size from bitrate and duration, or get a recommended bitrate from resolution and frame rate using a bits-per-pixel target.

Result

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How to use this calculator

Pick a mode: file size from bitrate, or recommended bitrate from resolution.
For file size, enter the video and audio bitrates and the duration.
For bitrate, enter width, height, frame rate, and a bits-per-pixel target.
Read the file size (or recommended bitrate) and the breakdown.

About this calculator

A video file's size is governed by its bitrate — the amount of data used per second — and its duration. This calculator works in two directions. In file-size mode it multiplies the total bitrate (video plus audio) by the running time and divides by eight to convert bits to bytes, giving the size of the finished file. In bitrate mode it estimates a sensible target bitrate for a given resolution and frame rate using a bits-per-pixel figure, which encodes how aggressively the codec compresses: H.264 at good quality is around 0.10 bits per pixel, while newer codecs like HEVC and AV1 reach similar quality at roughly half that. The file-size calculation is exact for a constant bitrate; the recommended-bitrate figure is a rule of thumb, since real encoders vary the bitrate with scene complexity.

How it works — the formula

Size = (Video Mbps + Audio kbps/1000) × Duration(s) × 10⁶ ÷ 8
Recommended bitrate ≈ Width × Height × FPS × bits-per-pixel

File size is total bitrate times duration in bits, converted to bytes. The recommended bitrate scales a per-pixel quality target by how many pixels are encoded per second.

Source: Wikipedia — Bit rate (encoding bit rate)

Worked examples

Example 1

8 Mbps video, no audio, 10 min

Inputs:: mode=size, videoBitrate=8, audioBitrate=0, minutes=10
Output:: 8e6 × 600 ÷ 8 = 600 MB (572 MiB)

Example 2

5 Mbps video + 192 kbps audio, 60 min

Inputs:: mode=size, videoBitrate=5, audioBitrate=192, minutes=60
Output:: ≈ 2.34 GB

Example 3

Recommended: 1920×1080, 30 fps, 0.1 bpp

Inputs:: mode=bitrate, width=1920, height=1080, fps=30, bpp=0.1
Output:: 6.22 Mbps

Limitations

Recommended-bitrate mode is a bits-per-pixel heuristic, not a codec model.
Assumes constant average bitrate; ignores container overhead.
Codec choice (H.264 vs HEVC/AV1) hugely changes the quality-per-bit.

File size is exact for a given bitrate; bitrate recommendations are starting points only.

Frequently asked

How do I calculate video file size?+

Multiply the total bitrate (video plus audio) by the duration in seconds, then divide by 8 to convert bits to bytes. For example, 8 Mbps over 10 minutes: 8,000,000 × 600 ÷ 8 = 600,000,000 bytes ≈ 572 MiB (600 MB).

What bitrate do I need for 1080p or 4K?+

It depends on frame rate and codec. As a bits-per-pixel rule of thumb at ~0.1 bpp for H.264: 1080p30 ≈ 6 Mbps, 1080p60 ≈ 12 Mbps, and 4K30 ≈ 25 Mbps. HEVC or AV1 reach similar quality at roughly half those numbers. Streaming platforms publish their own recommended ladders.

What is bits per pixel?+

It is the average number of compressed bits spent on each pixel each second of video (bitrate ÷ (width × height × fps)). Lower values mean more compression and smaller files; higher values mean better quality and bigger files. It is a convenient way to scale a bitrate across resolutions.

Why is GB different from GiB?+

GB (gigabyte) is decimal: 1 GB = 1,000,000,000 bytes. GiB (gibibyte) is binary: 1 GiB = 1,073,741,824 bytes. Operating systems often show GiB while labelling it "GB," which is why a file can look smaller than the marketing figure. This tool shows both.

Does this account for variable bitrate (VBR)?+

The file-size calculation assumes a constant average bitrate, which matches the average that VBR targets over the whole file. Instantaneous size varies scene to scene, but for total file size the average bitrate is what matters.

Should I add the audio bitrate?+

Yes, for an accurate total. Audio is usually small relative to video (e.g. 192 kbps vs several Mbps of video), but including it makes the estimate exact. Set audio to 0 if you only want the video stream size.