Understanding Video File Sizes: The Complete Guide
Whether you are recording gameplay for YouTube or archiving your Twitch streams, running out of hard drive space is a nightmare. This calculator helps you predict exactly how much storage you need before you hit record.
The Two Kings of File Size
Many people think 4K video is always bigger than 1080p. While usually true, resolution itself isn't what takes up space. It all comes down to two variables:
- Bitrate (Quality): How much data is allowed per second. Higher bitrate = better quality = larger file.
- Duration (Time): How long the recording is.
A 1080p video at 50,000 Kbps will be 5x larger than a 4K video at 10,000 Kbps. The bitrate controls the size, the resolution controls the pixel count.
What Bitrate Should I Used?
Here are the industry standards for different purposes:
For YouTube Uploads (High Quality)
If you edit and upload to YouTube, you want the highest quality possible before YouTube compresses it.
- 1080p 60fps: 15,000 - 20,000 Kbps
- 1440p 60fps: 30,000 - 40,000 Kbps
- 4K 60fps: 60,000 - 80,000 Kbps
For Twitch VODs / Streaming Archives
If you are just saving a copy of your stream, match your streaming bitrate.
- Twitch: 6,000 Kbps (CBR)
- YouTube Live: 10,000 - 15,000 Kbps
Pro Tip: Use CQP for Local Recordings
If you are recording locally, don't use a fixed bitrate (CBR). Use CQP (Constant Quantization Parameter) on NVIDIA cards or CRF on x264. This adjusts the bitrate dynamically—using less data for simple scenes (like menus) and more for action. It's much more efficient!
How to Reduce File Size
Running low on space? Here is how to shrink your files without ruining quality:
- Switch to H.265 (HEVC): This modern codec is 50% more efficient than the standard H.264. You get the same quality at half the file size.
- Lower the Framerate: Dropping from 60fps to 30fps cuts the required data significantly (though it won't look as smooth).
- Use MKV Format: Recording in MP4 is risky (files corrupt if OBS crashes). Record in MKV, then use OBS's "Remux Recordings" feature to convert to MP4 later if needed.