OBS Recording Size Guide: How Much Space Do You Need?
One of the worst feelings for a content creator is finishing a 4-hour recording session only to find out the file is corrupt because your hard drive ran out of space. Video files are huge. A single hour of high-quality 1080p footage can easily eat up 10GB or more. Understanding how bitrate affects file size is crucial for managing your storage.
The Math Behind File Sizes
File size is purely a function of Bitrate and Time. Resolution and FPS actually don't change the file size directly—they just determine how good that bitrate looks.
The formula is simple: (Bitrate in Kbps ÷ 8) × Seconds = Size in KB.
For example, recording at 10,000 Kbps for 1 hour (3600 seconds):
- 10,000 ÷ 8 = 1,250 KB per second (1.25 MB/s)
- 1.25 MB × 3,600 = 4,500 MB (4.5 GB)
CBR vs. CQP/CRF for Recording
Stop Using CBR for Recordings!
CBR (Constant Bitrate) forces the encoder to use the same amount of data for a black screen as it does for an explosion. This is wasteful and inefficient.
Instead, use CQP (Constant Quantization Parameter) for NVENC (NVIDIA) or CRF (Constant Rate Factor) for x264 (CPU). These modes adjust bitrate dynamically based on complexity. Simple scenes use less space; complex scenes use more.
Recommended Settings for Local Recording
If you have plenty of drive space, aim for "indistinguishable quality."
1080p 60fps (High Quality)
- Format: MKV (Remux to MP4 later). Never record directly to MP4 (if OBS crashes, the file is lost forever).
- Encoder: NVIDIA NVENC H.264 (New)
- Rate Control: CQP
- CQ Level: 15-20 (Lower is higher quality, bigger file sizes. 20 is a good sweet spot).
4K 60fps (Ultra Crisp)
- Rate Control: CQP
- CQ Level: 18-23
- Note: This eats storage alive. Expect 30-50GB per hour.
H.264 vs. H.265 (HEVC)
If you are short on space, switch to H.265 (HEVC). It is much more efficient than H.264, offering the same quality at 30-50% smaller file sizes. The only downside is that it is harder to edit in older video editing software (Premiere Pro handles it fine).