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Compress Audio

Compress audio to an exact size — MP3, M4A, OGG or FLAC, free.

  • Runs on your device
  • Exact podcast loudness targets
  • One file free · Batch with Pro
  • Free to 50 MB · Pro to your device

Drop audio here

Up to 50.0 MB and 10 minutes on Free · Takes MP3, WAV, OGG, M4A, AAC, FLAC

Settings
Preset
Preset

A starting point. Changing anything switches to Custom.

Output format
Output format

MP3 plays everywhere. FLAC keeps every sample.

Target
Target

Pick a quality level, or name the file size you need.

Bitrate
Bitrate
Pro

128 kbps suits speech; 192–256 kbps suits music.

Extra compression
50

Pushes the bitrate down further past halfway.

What This Audio Compressor Offers

It includes quick presets, live estimated output size, before/after waveform preview, and professional options so you can reduce file size while keeping control over quality.

  • Quick presets: Podcast ready, Music high quality, Mobile friendly, Email size, Speech optimized, Maximum compression—one click to apply recommended settings.
  • Estimated output size: See live estimated file size and reduction percentage before you compress, so you know what to expect.
  • Before/after waveform preview: Compare original and compressed audio with waveform visualizations and side-by-side playback.
  • Quality meter: Visual indicator (Excellent, Good, Voice optimized, Small size) based on your bitrate and format choices.
  • Loudness normalization: Target LUFS levels (e.g. -14 for Spotify/YouTube, -16 for podcast) for consistent volume across devices.
  • Trim silence: Remove silence at the start and end of files to reduce duration and file size.
  • Output formats: MP3, M4A, AAC, OGG (Opus), or lossless FLAC at 16 or 24-bit.
  • Re-compress: Change settings and compress again without re-uploading; ideal for trying different presets or bitrates.
  • Batch processing: Add multiple files, compress all at once, and download individually or as a ZIP.

Why Compress Audio Files?

Audio compression reduces file sizes, enables faster uploads and downloads, saves storage space, improves streaming performance, and ensures compatibility with size-limited platforms.

Benefits of Audio Compression

  • Reduced File Sizes: Compress audio files by 50-90% while maintaining quality
  • Faster Uploads: Smaller files upload and download much faster
  • Storage Savings: Save significant storage space on devices and servers
  • Better Streaming: Optimize audio for streaming platforms and websites
  • Email Compatibility: Reduce file sizes to meet email attachment limits

Audio Compression Explained

Audio compression reduces file size by removing redundant data and optimizing encoding. Understanding compression helps you achieve the best balance between file size and quality.

Lossy Compression

Removes audio data that's less perceptible to human hearing. MP3 and AAC use lossy compression, achieving significant size reduction with minimal quality loss at higher bitrates.

Lossless Compression

Reduces file size without losing any audio data. FLAC and ALAC use lossless compression, preserving perfect quality while achieving moderate size reduction.

Bitrate Guidelines

Choosing the right bitrate balances file size and audio quality for your specific needs.

Bitrate Recommendations

  • 64-96 kbps: Voice recordings, podcasts, low-quality needs
  • 128 kbps: Standard quality, web streaming, general use
  • 192 kbps: Good quality, music streaming, most applications
  • 256-320 kbps: High quality, professional use, audiophiles

Common Use Cases

Audio compression serves various purposes across different platforms and industries.

Music Streaming

Compress audio files for streaming platforms like Spotify, YouTube Music, and SoundCloud. Most platforms use 128-320 kbps compression.

Podcast Production

Optimize podcast episodes for faster downloads and reduced hosting costs. Voice content can be compressed more aggressively than music.

Website Integration

Compress audio files for website backgrounds, sound effects, and embedded media. Smaller files improve page load times significantly.

Storage Management

Reduce audio file sizes to free up space on devices, cloud storage, and servers. Compress large music libraries efficiently.

How Audio Compression Works

Audio compression uses advanced algorithms to reduce file size while maintaining audio quality. Understanding the process helps you achieve optimal compression results.

Compression Process

  • Format and codec: Choose output format (MP3, M4A, AAC, OGG, FLAC) and options such as a target file size, loudness for low-bitrate AAC, or FLAC compression level.
  • Bitrate and quality: Set bitrate (64–320 kbps for lossy) or use a preset. The live estimated output and quality meter help you balance file size and quality.
  • Filters and normalization: Optional loudness normalization (LUFS), trim silence at start/end, band presets (Music, Speech, Voice), and dynamic range compression reduce size and improve consistency.
  • Sample rate and channels: Optionally set sample rate (e.g. 44.1 kHz, 22.05 kHz, 8 kHz) and mono/stereo to further reduce file size when appropriate.

How to Compress Audio Files Online

Learn how to compress audio files with presets, estimated output, and before/after waveform preview using our free online audio compressor.

  1. Add Your Audio. Drop or select audio files. Supported formats include MP3, WAV, AAC, OGG, FLAC, M4A. Files load; nothing is uploaded. You can add multiple files for batch processing.
  2. Choose Settings or a Preset. Use a quick preset (Podcast ready, Music high quality, Mobile friendly, Email size, Speech optimized, Maximum compression) for one-click setup, or adjust output format (MP3, M4A, AAC, OGG, FLAC), bitrate, target file size, sample rate, channels, loudness normalization (LUFS), trim silence, and dynamic range. The tool shows live estimated output size and reduction percentage.
  3. Click Compress. Click the Compress button to start processing. Audio is compressed. Estimated processing time is shown. You can re-compress with different settings at any time.
  4. Preview and Download. Compare before and after using the waveform preview and audio players. Check the quality meter and file size reduction. Download individual files or all as a ZIP. All processing is on-device for privacy.
  5. Batch and Re-compress. Upload multiple files and compress all at once. Change settings and click Re-compress to apply new options (e.g. different bitrate or preset) without re-uploading.

Audio Compression Facts

Understanding these facts helps you make better compression decisions.

Key Statistics

  • MP3 compression can reduce file sizes by 75-90% compared to WAV
  • 128 kbps MP3 is suitable for most listening purposes
  • 192 kbps MP3 provides near-CD quality for most listeners
  • 320 kbps MP3 is considered high quality for most applications
  • Compressed audio files load 3-5x faster than uncompressed formats

Powered by optimised audio processing algorithms.

Frequently Asked Questions

Why does re-encoding my MP3 at the same bitrate still reduce quality?

Each lossy encode discards audio data. Re-encoding an already compressed MP3 at the same bitrate stacks a second round of loss on top of the first. Always compress from the highest-quality source available — ideally WAV or FLAC — to minimize cumulative quality loss.

What is the smallest file size I can reach for a one-hour podcast and still keep speech clear?

A one-hour voice podcast at 64 kbps mono MP3 is around 28 MB and remains intelligible for most listeners. The Podcast ready preset applies 128 kbps mono with -16 LUFS normalization and silence trimming, producing roughly 57 MB per hour, which is standard for most podcast hosts.

Does the before/after waveform comparison show audio quality differences?

The waveform shows level and dynamic range changes — such as the effect of loudness normalization — but it cannot visually reveal codec artifacts or frequency loss. Use the before/after audio players at matched volume for the most reliable quality comparison.

How accurate are the loudness targets?

Loudness is measured to ITU-R BS.1770-4, the same standard broadcasters and streaming services use — K-weighted, gated, and integrated across the whole recording rather than a simple average level. The tool applies one correction to reach your target and checks it will not push the peak past −1 dBTP. Measured against both a very quiet source and a very loud one, every target landed within 0.01 LU. Choose Streaming (−14), Podcast (−16), Broadcast (−23), or set your own.

Can I compress a FLAC file and still keep lossless audio quality?

Yes. Export as FLAC with a higher compression level (5–8) to reduce file size with zero quality loss. FLAC uses mathematical compression that discards no audio data. Higher levels take longer to encode but produce smaller files.

Can I compress to an exact file size?

Yes. Switch the target from By quality to By file size and enter the number of megabytes you need. The tool works out the bitrate for your recording's length, encodes, measures the result and corrects once if it missed — so a 5 MB request lands at or just under 5 MB rather than somewhere near it. That is the usual reason people compress audio at all: an attachment limit, an upload cap, or a storage budget. File size targeting is not offered for FLAC, because lossless output size is decided by the recording rather than by a setting.

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