Free Audio Compressor Online
Even out volume dynamics with adjustable threshold, ratio, attack & release. Professional presets for voice, music & podcasts. No install, no sign up. 100% private.
Dynamic Range Compression
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or click to browse • MP3, WAV, FLAC, OGG, M4A, WebM, AIFF, MP4 • Max 50MB
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Audio Compression for Beginners: Threshold, Ratio, Attack & Release Explained
Compression is the most misunderstood tool in audio — and the most powerful. Used correctly, it makes podcasts sound professional, vocals sit perfectly in a mix, and recordings feel polished. Used incorrectly, it crushes dynamics and makes audio sound lifeless. This guide explains exactly what each parameter does with real-world settings you can copy.
What Does a Compressor Actually Do?
A compressor is an automatic volume control. It watches the audio level and turns down the volume whenever it gets too loud. Specifically:
- Audio plays normally until it crosses the threshold
- Once above the threshold, the compressor reduces the volume according to the ratio
- Attack controls how quickly the compressor reacts
- Release controls how quickly it stops compressing after the loud part ends
- Makeup gain boosts the overall level back up after compression
The 5 Parameters Explained Simply
| Parameter | What It Controls | Simple Analogy | Typical Range |
|---|---|---|---|
| Threshold | When compression starts | "The volume level that triggers the automatic volume knob" | -60dB to 0dB |
| Ratio | How much compression | "How aggressively the volume knob turns down" | 1:1 to 20:1 |
| Attack | How fast it reacts | "How quickly your hand reaches for the volume knob" | 1ms to 100ms |
| Release | How fast it recovers | "How quickly your hand lets go of the volume knob" | 10ms to 1000ms |
| Makeup Gain | Volume compensation | "Turning the volume back up after compression made it quieter" | 0dB to +12dB |
Understanding Ratio with Examples
| Ratio | Input Over Threshold | Output | Effect |
|---|---|---|---|
| 1:1 | +10dB | +10dB | No compression (bypass) |
| 2:1 | +10dB | +5dB | Gentle compression |
| 4:1 | +10dB | +2.5dB | Moderate (most common) |
| 8:1 | +10dB | +1.25dB | Heavy compression |
| 20:1 | +10dB | +0.5dB | Limiting (brick wall) |
Rule of thumb: 2:1 to 4:1 for natural-sounding compression. 6:1 to 8:1 for aggressive control. Above 10:1 is essentially a limiter. Start with 4:1 and adjust from there.
Best Compressor Settings by Use Case
| Use Case | Threshold | Ratio | Attack | Release | Makeup |
|---|---|---|---|---|---|
| Podcast / Voice | -20 dB | 3:1 | 15 ms | 250 ms | +3 dB |
| Music (general) | -18 dB | 3:1 | 20 ms | 300 ms | +2 dB |
| Vocals in a mix | -24 dB | 4:1 | 10 ms | 200 ms | +3 dB |
| Drums / Percussion | -15 dB | 4:1 | 5 ms | 150 ms | +2 dB |
| Bass guitar | -20 dB | 5:1 | 10 ms | 200 ms | +3 dB |
| Aggressive / Broadcast | -30 dB | 8:1 | 5 ms | 100 ms | +6 dB |
| Mastering (subtle) | -10 dB | 2:1 | 30 ms | 300 ms | +1 dB |
How to Compress Audio Online (Step-by-Step)
- Upload your audio to the compressor above
- Start with a preset — Voice, Music, Podcast, or Aggressive. This gives you a solid starting point.
- Adjust the threshold — Lower it until you see the gain reduction meter moving during the loudest parts. Aim for 3-6dB of gain reduction.
- Fine-tune the ratio — Higher ratios (6:1+) for more aggressive control, lower ratios (2:1-3:1) for subtle smoothing.
- Set attack and release — Fast attack (5-15ms) for voice. Medium attack (20-50ms) for music. Release around 200-300ms for natural sound.
- Add makeup gain — Compression reduces overall volume. Add makeup gain to bring it back up. Match the perceived loudness to the original.
- Preview and export — Compare with the original, then export as WAV.
Compressor vs. Normalizer vs. Limiter
| Tool | What It Does | When to Use |
|---|---|---|
| Compressor | Reduces dynamic range (loud parts get quieter) | Uneven volume, podcast with loud/quiet speakers |
| Normalizer | Adjusts overall volume to a target | Audio is uniformly too quiet or too loud |
| Limiter | Hard ceiling — nothing goes above the limit | Final stage before export, preventing clipping |
Pro workflow: Compress first (to even out dynamics) → Normalize second (to set final volume) → Use our Volume Booster if you need extra loudness with anti-clipping.
Common Compression Mistakes
- Threshold too low: Everything gets compressed, making audio sound flat and lifeless. Raise the threshold so only the peaks trigger compression.
- Ratio too high: 10:1+ on voice sounds robotic. Use 3:1-4:1 for natural results.
- Attack too fast: Kills transients (the initial "punch" of sounds). For drums and percussive music, use 20-50ms attack to preserve impact.
- Release too short: Causes "pumping" — audible volume fluctuations. Use 200ms+ for smooth, transparent compression.
- Too much makeup gain: Defeats the purpose of compression and can cause clipping. Keep makeup gain modest (+2 to +6dB).
Related Tools
- Need to normalize volume after compressing? → Audio Normalizer
- Want to boost volume safely? → Volume Booster
- Need to remove noise before compressing? → Noise Reducer
- Want to remove silence from recordings? → Silence Remover
- Need to EQ the result? → 5-Band Equalizer
How to Compress Audio Online
Upload Your Audio
Drag and drop or browse to select your audio file. We support MP3, WAV, FLAC, OGG, M4A, WebM, AIFF, and MP4 formats up to 50MB.
Choose a Preset or Adjust Manually
Select Voice, Music, Podcast, or Aggressive preset. Or manually adjust threshold, ratio, attack, release, and makeup gain.
Preview the Result
Click "Play Preview" to hear the compressed audio. Click anywhere on the waveform to play from a specific section.
Export & Download
When satisfied, click "Export & Download" to save your compressed audio as a high-quality WAV file.
Why Use ChangerAudio Compressor?
No Sign Up
No account needed. Just open and start compressing instantly.
Full Control
5 adjustable parameters: threshold, ratio, attack, release, makeup gain.
100% Free
No watermarks, no limits. Forever free for all use cases.
Pro Presets
4 calibrated presets for voice, music, podcasts, and aggressive compression.
Frequently Asked Questions
What does an audio compressor do?
A compressor reduces the dynamic range of audio by lowering the volume of loud sounds that exceed a threshold, then optionally boosting the overall level with makeup gain. This makes quiet and loud parts more consistent, which is essential for podcasts, voice recordings, and music production.
What do threshold, ratio, attack, and release mean?
Threshold: the volume level where compression starts. Ratio: how much compression is applied (4:1 means 4dB over threshold becomes 1dB). Attack: how fast compression engages. Release: how fast compression disengages. Makeup gain: compensates for volume lost during compression.
What are good compressor settings for podcasts?
For podcasts: Threshold -20dB, Ratio 3:1, Attack 15ms, Release 250ms, Makeup Gain +3dB. This evens out volume differences between speakers without sounding over-processed.
Should I compress before or after EQ?
Generally, compress first then EQ. Compression evens out dynamics, then EQ shapes the tone. However, if you have problematic frequencies (like rumble), EQ those out first so the compressor doesn't react to them.
Is the audio compressor free?
Yes, 100% free with no watermarks, no sign up, and no limits. All processing happens locally in your browser — your files are never uploaded to a server.