Video File Size Calculator

Video file size depends on resolution, duration, bitrate, and format. A 5-minute 1080p MP4 is roughly 75 MB at standard streaming quality. Use this calculator to estimate your file size instantly.

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How the calculation works

File size is determined by bitrate and duration. The formula is straightforward:

File size (MB) = (Bitrate in Mbps × Duration in seconds) / 8

Dividing by 8 converts from megabits to megabytes. The bitrate assumptions used here are standard averages for each resolution at typical streaming quality:

Resolution Assumed bitrate Typical use
360p 1 Mbps Mobile, low bandwidth
480p 2.5 Mbps Standard definition
720p 5 Mbps HD streaming
1080p 8 Mbps Full HD
1440p 16 Mbps 2K / QHD
4K 35 Mbps Ultra HD

Format also matters. WebM (VP9) is roughly 30% more efficient than MP4 (H.264) at the same visual quality, so the same video will be smaller in WebM. MOV files tend to be slightly larger than MP4 as they often use less aggressive compression settings by default.

Upload limits on major platforms

If you're downloading a video and re-uploading it somewhere, knowing the platform's file size limit matters:

If you're trying to pick a tool for downloading videos from any of these platforms, the video downloader comparison has a breakdown of what works best in 2026.

Common questions

How accurate is this calculator?
The estimates are based on standard average bitrates for each resolution. Real file sizes vary depending on content complexity, the specific codec and encoder settings used, and how much motion is in the video. A static talking-head video at 1080p will be smaller than an action-packed clip at the same resolution. Use these numbers as a ballpark, not a precise prediction.
What affects video file size?
The four main factors are: resolution (higher resolution = more pixels = larger file), duration (longer video = larger file), bitrate (how much data per second the encoder uses), and content complexity (lots of movement and detail requires more data to encode than simple, static scenes). The codec also matters - H.265/HEVC can store the same quality as H.264 in roughly half the space.
What's the best format for sharing on social media?
MP4 with H.264 encoding is the most universally compatible format across every platform - TikTok, Instagram, Twitter, Facebook, YouTube all accept it without issues. WebM is more efficient but not supported everywhere. MOV works well on Apple devices and is fine for uploading, but it's a container format that can hold different codecs, so compatibility depends on what's inside.