How to Use the Video Bitrate & Size Calculator
A video file's size is determined by its bitrate (data per second) multiplied by its duration. A higher bitrate packs more quality information into each second, improving picture quality but also increasing file size. Most video files store a video stream and an audio stream together, so an accurate size estimate needs to add both bitrates.
This calculator takes your video bitrate (Mbps), audio bitrate (kbps), and duration (minutes), then estimates the resulting file size in MB and GB. It's useful for previewing upload size before posting to YouTube or social media, or for choosing encoding settings before saving video to a device with limited storage. If you already have a target file size in mind, you can work the math backward to find the bitrate you need.
Frequently Asked Questions
Generally yes — a higher bitrate packs more data per second, improving quality. However, the perceived difference depends on the codec's efficiency.
Divide your target size in MB by the duration in seconds, then multiply by 8 to get the total required bitrate in Mbps. Subtract the audio bitrate to get the video bitrate.