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Comparison

CRF vs Bitrate

Which should you use?

Quick verdict

Use CRF when you want consistent perceptual quality and flexible file size - ideal for one-off encodes and archives. Use target bitrate (or 2-pass) when you must hit a specific file size or a fixed streaming data rate.

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CRF (Constant Rate Factor) and target bitrate are two ways to control the output of an x264/x265 encode. They answer different questions: CRF asks how good should it look, while target bitrate asks how big should it be. The right choice depends on whether quality or file size is your fixed constraint.

With CRF you set a quality level and the encoder spends as many or as few bits as each scene needs, so the final size varies. With target bitrate you fix the data rate and quality varies with scene complexity. A 2-pass encode at a target bitrate analyzes the video first to distribute those bits more wisely.

At a glance

PropertyCRFBitrate
What it fixesPerceptual qualityData rate / size
What variesFile sizeQuality per scene
Predictable sizeNoYes
Best forOne-off encodes, archivesStreaming, upload limits
Passes neededSingle pass1-pass or 2-pass
Lower value meansBetter quality, bigger fileSmaller file, lower quality

Choose CRF when

  • You want consistent quality across the whole video
  • The final file size does not need to be exact
  • You are doing one-off encodes, re-encodes, or local archives
  • You want the fastest single-pass workflow

Choose Bitrate when

  • You must meet a hard file size limit
  • You are streaming at a fixed data rate
  • An upload or platform caps the bitrate
  • You want 2-pass for the best quality at an exact size

Frequently asked questions

Is CRF better than bitrate?
Neither is universally better; they optimize for different goals. CRF gives consistent quality with a variable file size, while target bitrate gives a predictable size with variable quality. Use CRF for quality-first encodes and target bitrate when size or stream rate is fixed.
What CRF value should I use?
For x264, CRF 18-23 is the common range, with 23 as the default and 18 looking visually near-lossless. Lower values mean higher quality and bigger files. x265 uses a similar scale but defaults to CRF 28, which is roughly equivalent to x264's CRF 23.
When should I use 2-pass instead of CRF?
Use 2-pass when you need to hit a specific file size or average bitrate, such as for streaming or platform upload limits. The first pass analyzes the video so the second pass can distribute bits efficiently, giving better quality than 1-pass at the same target size.
Does CRF produce a predictable file size?
No. CRF holds quality constant and lets the file size float based on how complex the footage is, so the final size is hard to predict in advance. If you need a known size, use a target bitrate, ideally with 2-pass encoding.

Related tools

Online Video CompressorVideo Bitrate Calculator

Related terms

CRF (Constant Rate Factor)Bitrate