What Does Compressor Ratio Mean?
Ratio is measured as input change compared with output change above the threshold. At 2:1, every 2 dB above the threshold becomes about 1 dB at the output. At 4:1, every 4 dB above the threshold becomes about 1 dB. This is why ratio changes the strength of compression without deciding when compression begins; threshold handles the starting line.
Imagine a threshold is already set, and a loud word rises 8 dB above it. With 2:1 compression, the excess is reduced to about 4 dB. With 4:1, it becomes about 2 dB. With 8:1, it becomes about 1 dB. The voice is not muted; the part that crossed the threshold is made less extreme.
| If signal is 8 dB over threshold | Remaining level above threshold | Result |
|---|
| 2:1 ratio | About 4 dB | Gentle leveling |
| 4:1 ratio | About 2 dB | Firm voice control |
| 8:1 ratio | About 1 dB | Very strong compression |
Common Ratio Values
Ratio ranges are easier to use when you connect the number to a sound character. Low ratios preserve movement. Medium ratios control uneven sources. High ratios are special-purpose tools that can quickly become obvious.
| Ratio | Character | Typical Use |
|---|
| 1.5:1 | Very subtle, almost transparent | Mix bus, gentle music leveling, background music |
| 2:1 | Natural and forgiving | Voice-over, acoustic instruments, light podcast control |
| 3:1 | Noticeable but still smooth | Podcast voice, narration, streaming speech |
| 4:1 | Firm control | Vocal peaks, inconsistent speech, bass guitar |
| 6:1 | Strong compression | Aggressive vocal control, drums, energetic sources |
| 10:1 | Limiter-like behavior | Peak control when a source jumps sharply |
| 20:1 and above | Very strict limiting territory | Safety limiting, special effects, clipping prevention with ceiling control |
Low Ratio vs High Ratio
A low ratio lets the listener still hear the natural rise and fall of the performance. It is useful when the recording is already good and only needs mild help. For speech, 2:1 can gently reduce the loudest words without making the voice feel trapped.
A high ratio makes the compressor more obvious because the loudest parts stop moving as freely. This can be useful for a livestream microphone that must not jump out, or for a bass part that needs to stay locked in place. It can also remove expression if the threshold is too low. High ratio plus fast attack often creates a tight, dense sound that beginners may mistake for professional loudness.
- Low ratio: more natural, less control, better for transparent leveling.
- Medium ratio: good balance for speech, podcast, and general vocal work.
- High ratio: stronger peak control, higher risk of audible pumping or flatness.
- Limiter-like ratio: useful for safety, not a replacement for good gain staging.
Ratio for Voice, Podcast, Music, and Streaming
Choose ratio based on how uneven the source is and how polished the result needs to be. A close-mic podcast voice may need more control than a calm voice-over. Drums may use higher ratios for attitude, while a full music bus often uses lower ratios because too much compression affects the whole mix at once.
| Source | Starting ratio | Why |
|---|
| Speech recording | 2:1 to 3:1 | Keeps words understandable while preserving natural delivery |
| Podcast voice | 3:1 to 4:1 | Controls guest level changes and louder phrases |
| Lead vocal | 3:1 to 6:1 | Depends on genre, singer dynamics, and desired density |
| Drum room or snare | 4:1 to 8:1 | Can add energy and reduce sharp peaks |
| Bass | 3:1 to 6:1 | Helps notes stay more even |
| Streaming mic | 3:1 to 5:1 | Keeps sudden loud words manageable without sounding crushed |
Ratio vs Limiter
A limiter is often described as a compressor with a very high ratio, but that is only part of the story. Limiters usually include a ceiling, very fast response, and stricter peak control so the output does not pass a set maximum level. A 10:1 or 20:1 compressor can behave limiter-like, but it may not protect the final output the way a true limiter does.
If your question is whether to use a compressor or limiter on a voice, stream, or final master, read Audio Compressor vs Limiter. Ratio is one bridge between them, but ceiling and timing decide how safe the output really is.
Ratio Does Not Directly Control File Size
Ratio is not bitrate. A 4:1 compressor setting does not mean the file becomes one quarter of the size. It only describes how strongly loud signal above the threshold is reduced. You can export a heavily compressed voice as a huge WAV, or a lightly compressed voice as a small MP3.
If the goal is reducing MB, use the Audio Compressor and choose lower bitrate, a more efficient format, mono speech, or target size. Dynamic compression can improve listening consistency before export, but file compression decides the size.
Ratio changes how strongly loud parts are reduced. To reduce MB size, switch to file compression and choose a lower bitrate or target size.