How to Reduce OBS Studio Recording File Size

If your OBS Studio recordings are taking up massive amounts of hard drive space, it is usually due to improper bitrate configurations, inefficient encoders, or lossless quality settings. This guide explains why your OBS recording file sizes are excessively large and provides straightforward, step-by-step solutions to reduce their size while maintaining excellent video quality.

Why Your OBS Recordings Are So Large

The primary culprit behind bloated OBS file sizes is the bitrate—the amount of data processed per second. If your settings are configured to “Lossless” or an excessively high constant bitrate (CBR), OBS will write massive amounts of data to your drive. Additionally, using outdated encoders or recording at unnecessary resolutions and frame rates (like 4K at 60 FPS) will exponentially increase file sizes.

How to Reduce OBS File Size

To optimize your storage without sacrificing noticeable video quality, adjust the following settings in OBS Studio by navigating to Settings > Output and selecting the Recording tab. (Make sure your “Output Mode” at the top is set to Advanced).

1. Change the Rate Control to CQP or CRF

Do not use CBR (Constant Bitrate) for recording; CBR is designed for live streaming. Instead, use CQP (Constant QP) or CRF (Constant Rate Factor). These methods allocate bitrate dynamically based on the complexity of the scene.

• Set Rate Control to: CQP (for hardware encoders) or CRF (for x264 software encoder).
• Adjust the CQ Level / CRF value: A value between 20 and 23 is the sweet spot for balance between quality and file size.
  • Note: Lower numbers yield higher quality but larger files. Raising the value to 24 or 25 will drastically reduce file size with only a minor loss in visual fidelity. Avoid values below 16 unless you have terabytes of free space.

2. Switch to a Hardware Encoder

Encoding video using your CPU (x264) can be inefficient. Utilizing your graphics card’s dedicated hardware encoder reduces CPU load and compresses files more efficiently.

• NVIDIA Users: Select NVIDIA NVENC H.264 or NVIDIA NVENC HEVC (H.265).
• AMD Users: Select AMD HW H.264 or AMD HW HEVC.
• Intel Users: Select Intel QuickSync.
• Tip: If available, HEVC (H.265) or AV1 encoders offer significantly better compression than standard H.264, allowing you to get the same video quality at a much smaller file size.

3. Lower Your Resolution and Frame Rate

High-definition video requires more data. If you are recording in 4K or 1440p, downscaling to 1080p will instantly shrink your files.

Go to Settings > Video: * Base (Canvas) Resolution: Set this to your monitor’s native resolution. * Output (Scaled) Resolution: Set this to 1920x1080 (or 1280x720 for even smaller files). * Common FPS Values: Drop this from 60 to 30 if you are recording tutorials, presentations, or slow-paced games. This instantly cuts the number of rendered frames in half.

4. Choose the Right Recording Format

Go to Settings > Output > Recording and check your Recording Format.

• Use MKV or Fragmented MP4.
• Avoid using standard MP4 directly, as your file will be corrupted if OBS or your system crashes. If you need MP4 files for editing, go to Settings > Advanced and check the box for Automatically remux to mp4. OBS will record in a safe format (like MKV) and instantly convert it to a highly compressed MP4 when you stop recording.