Compress Audio to Reduce File Size

Support for 23 audio formats. Adjust bitrate, sample rate, and quality settings for optimal compression.

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Supports all audio formats • Multiple files • Secure compression

23 Audio Formats

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Quality Control Settings

-79% Best Measured Saving

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What You Can Control

Pick a preset, choose an output format, and the compressor handles the rest.

Quality Preset

Fast, Normal, Maximum or Ultra. Each sets the target bitrate: 96k, 192k, 256k or 320k.

Output Format

Compress to any of 23 formats. Switching codec is often a bigger saving than lowering the bitrate.

Batch Compression

Drop several files at once and compress them all in a single pass.

Browser or Server

Compress locally so files never leave your device, or switch to server mode for files up to 100 MB.

Which Preset Should You Use?

Six answers taken straight from the measurements above.

Best overall

OPUS Fast, 96k

1.46 MB, -79%, -0.3 dB

Cuts the file by 79% while staying 0.3 from the original, the best result in the entire test. MP3 at the same preset loses 7.0 for a smaller saving.

Best quality kept

OGG Normal, 192k

2.86 MB, -58%, -0.0 dB

Measured at -0.0 against the source while still removing 58% of the file size. Nothing else in the test kept more detail at a comparable saving.

Staying on MP3

MP3 Normal, 192k

4.12 MB, -40%, -1.5 dB

When the file has to remain an MP3, 192k is the sensible floor: 40% smaller for 1.5 of loss. Dropping to 96k saves more but costs 7.0.

Biggest saving

OPUS Fast, 96k

-79% from 6.87 MB to 1.46 MB

The largest reduction that still holds quality. OGG at the same bitrate saves 77% but gives up 3.3 against Opus's 0.3.

Apple devices

AAC Normal, 192k

4.16 MB, -39%, -0.8 dB

Plays natively everywhere in the Apple ecosystem and keeps within 0.8 of the source. Worth noting AAC was the slowest encoder in the test at 3.52s.

Skip this one

MP3 Ultra, 320k

no size change

Re-encoding a 320k MP3 at 320k returned a file of exactly the same size, so there is nothing to gain. Repeated re-encoding at this rate measured no meaningful quality change either, so it is simply wasted time rather than damaging.

How Much Smaller, and What It Costs

A 6.87 MB 320 kbps MP3 compressed 16 ways, with every result measured.

Format	Preset	Bitrate	Size	Reduction	Detail Kept	Quality
MP3	Fast	96k	2.06 MB	-70%	-7.0 dB	Audibly dulled
AAC	Fast	96k	2.10 MB	-69%	-5.7 dB	Audibly dulled
OPUS	Fast	96k	1.46 MB	-79%	-0.3 dB	Nearly identical
OGG	Fast	96k	1.56 MB	-77%	-3.3 dB	Audibly dulled
MP3	Normal	192k	4.12 MB	-40%	-1.5 dB	Noticeable on good gear
AAC	Normal	192k	4.16 MB	-39%	-0.8 dB	Very close
OPUS	Normal	192k	3.11 MB	-55%	-0.2 dB	Nearly identical
OGG	Normal	192k	2.86 MB	-58%	-0.0 dB	Nearly identical
MP3	Maximum	256k	5.50 MB	-20%	-0.6 dB	Very close
AAC	Maximum	256k	4.99 MB	-27%	-0.2 dB	Nearly identical
OPUS	Maximum	256k	4.43 MB	-35%	-0.2 dB	Nearly identical
OGG	Maximum	256k	3.61 MB	-48%	-0.3 dB	Nearly identical
MP3	Ultra	320k	6.87 MB	none	-0.0 dB	Nearly identical
AAC	Ultra	320k	4.99 MB	-27%	-0.2 dB	Nearly identical
OPUS	Ultra	320k	5.75 MB	-16%	-0.2 dB	Nearly identical
OGG	Ultra	320k	4.62 MB	-33%	-0.3 dB	Nearly identical

Measured with FFmpeg 7.1. The input was a 6.87 MB 320 kbps MP3, which is what people usually have rather than a studio master, so the reduction column shows what you would actually save on a typical file. Quality is the change in energy above 16 kHz against that input: lossy encoders discard the top of the spectrum first, so the drop shows how much detail each setting gave up. It measures retained detail, not listening preference, and it is not a substitute for a blind listening test.

Best Settings by Destination

Where the file is going decides how hard you should compress.

Email Attachments

Most providers cap attachments at 25 MB. Opus or MP3 at 96k fits roughly an hour of audio inside that limit.

Podcast Hosting

MP3 at 128k mono for speech. Every podcast platform accepts it, and voice does not benefit from stereo or higher rates.

Websites & Web Apps

Opus at 96k gives the smallest file modern browsers can play, with an MP3 fallback for older ones.

Music Libraries

AAC or OGG at 192k. Small enough to store thousands of tracks, close enough to the source that the difference is hard to hear.

Voice Notes & Calls

Opus at 64k with a 22.05 kHz sample rate. Speech carries almost no high-frequency content, so the reduction costs nothing that matters.

Archiving

Do not compress at all. Keep FLAC or the original file: every lossy pass throws away detail you cannot get back.

Supported Audio Formats

Compress between 23 audio formats with full quality control - adjust bitrate, sample rate, and channels

Common Encodings

MP3

MPEG-1 Audio Layer III - the most universal audio format worldwide, using lossy compression to reduce file sizes by 90% while maintaining excellent perceived quality. Perfect for music libraries, podcasts, portable devices, and any scenario requiring broad compatibility. Supports bitrates from 32-320kbps. Standard for digital music since 1993, playable on virtually every device and platform.

WAV

Waveform Audio File Format - uncompressed PCM audio offering perfect fidelity with zero quality loss. Standard format for audio editing, professional recording, and mastering workflows. Large file sizes (10MB per minute at CD quality) but instant playback and editing. Native Windows format, universally supported across all platforms. Essential for professional audio work and archival masters.

OGG

Ogg Vorbis - open-source lossy compression format offering superior quality compared to MP3 at equivalent bitrates. Free from patent restrictions, making it popular in open-source software, games, and web applications. Excellent for music streaming at 128-256kbps. Better low-frequency reproduction than MP3. Standard format in many video games and Linux applications.

AAC

Advanced Audio Coding - successor to MP3 offering 20-30% better compression efficiency at equivalent perceived quality. Standard format for Apple devices (iTunes, iPhone, iPad), YouTube, streaming services, and modern applications. Supports up to 256kbps with near-transparent quality. Part of MPEG-4 standard. Excellent for music, podcasts, and multimedia applications.

FLAC

Free Lossless Audio Codec - open-source format providing perfect bit-for-bit audio reproduction with 40-60% file size reduction compared to WAV. No quality loss during compression or decompression. Standard for audiophile music libraries, archival storage, and when pristine quality matters. Supports high-resolution audio up to 32-bit/384kHz. Ideal for master recordings and digital music collections.

M4A

MPEG-4 Audio file containing AAC or ALAC encoded audio. Native format for iTunes, Apple Music, and iOS devices. Supports both lossy (AAC) and lossless (ALAC) compression in same container format. Better metadata support than MP3 including chapter markers, artwork, and lyrics. Standard for Apple ecosystem and increasingly popular across platforms.

WMA

Windows Media Audio - Microsoft's proprietary lossy audio format competing with MP3 and AAC. Developed for Windows Media Player and Windows ecosystem. Offers good compression at 128-192kbps. Native support on Windows devices but limited compatibility elsewhere. Includes DRM (Digital Rights Management) capabilities. Common in Windows-based audio applications and legacy media libraries.

Lossless Encodings

ALAC

Apple Lossless Audio Codec - proprietary lossless format from Apple offering perfect audio reproduction with 40-50% compression. Native support in iTunes, iOS, macOS, and Apple TV. Equivalent quality to FLAC but with better Apple ecosystem integration. Supports up to 24-bit/192kHz high-resolution audio. Ideal for iTunes users wanting lossless quality and for Apple device libraries.

APE

Monkey's Audio - lossless compression format achieving the highest compression ratios among lossless codecs (typically 55% of original size). Slower encoding/decoding than FLAC but produces smaller files. Popular in archival and bandwidth-limited scenarios. Supports up to 24-bit audio. Free format with Windows-focused development but cross-platform players available.

WavPack - unique hybrid lossless/lossy format allowing both modes in single codec. Lossless mode achieves FLAC-comparable compression with faster decoding. Hybrid mode creates small lossy file with correction data for lossless reconstruction. Supports high-resolution audio up to 32-bit float. Excellent for flexible archival (keep lossless, distribute lossy) and professional workflows.

TTA

True Audio - simple, efficient lossless codec focusing on speed and compression ratio. Real-time encoding/decoding even on modest hardware. Achieves similar compression to FLAC with slightly faster performance. Open-source and free. Supports up to 24-bit audio at various sample rates. Popular in Eastern Europe and among users prioritizing encoding speed for large music collections.

AIFF

Audio Interchange File Format - Apple's uncompressed audio standard, equivalent to WAV but with different metadata structure. Standard for professional audio on Mac systems. Supports up to 32-bit audio at any sample rate. Common in music production, sound design, and professional recording. Better metadata support than WAV. Essential format for Mac-based audio workflows and cross-platform professional projects.

Modern Encodings

OPUS

Opus - cutting-edge audio codec (2012) offering best-in-class quality at all bitrates from speech (8kbps) to high-fidelity music (256kbps). Significantly outperforms MP3, AAC, and Vorbis in quality-to-bitrate efficiency. Excellent for streaming, VoIP, podcasts, and web audio. Low latency makes it perfect for real-time communication. Free and open-source. Future of audio compression but still gaining device compatibility.

WEBM

WebM Audio - web-optimized container format typically containing Opus or Vorbis audio. Developed by Google for HTML5 video/audio. Royalty-free and open-source. Native support in all modern browsers. Excellent for web streaming, podcasts, and online audio applications. Part of Google's push for open web standards. Ideal for web developers and online content creators.

MKA

Matroska Audio - flexible container format supporting any audio codec (FLAC, AAC, MP3, Opus, etc.) with extensive metadata and chapter support. Open-source alternative to proprietary containers. Excellent for audiobooks with chapters, podcasts with segments, and complex audio projects. Supports multiple audio tracks and subtitles. Growing adoption in media applications requiring advanced features.

Legacy Encodings

MP2

MPEG-1 Audio Layer II - predecessor to MP3, offering simpler encoding with less compression efficiency. Standard in broadcasting (Digital Audio Broadcasting - DAB, Digital Video Broadcasting - DVB) due to low latency and simple decoding. Still used in professional video production (DVD, SVCD). Typical bitrates 192-384kbps. Historical format maintained for compatibility with broadcast equipment and legacy DVD authoring.

AC3

Dolby Digital (Audio Codec 3) - standard surround sound format for DVDs, Blu-rays, digital television, and theatrical releases. Supports up to 5.1 channels with efficient compression. Bitrates typically 192-640kbps. Essential for home theater systems and multi-channel audio. Proprietary format requiring licensing but ubiquitous in consumer electronics. Standard for DVD/Blu-ray audio tracks and digital broadcasting.

AMR

Adaptive Multi-Rate - speech codec optimized for mobile voice communications (GSM, 3G). Very low bitrates (4.75-12.2kbps) with acceptable speech quality. Designed for phone calls, not music. Dynamically adjusts bitrate based on network conditions. Essential for mobile telephony but obsolete for general audio. Used in voice messaging, call recording, and legacy mobile applications.

Sun Microsystems Audio format (.au or .snd) - one of oldest digital audio formats from Unix workstations (1980s). Simple header followed by raw audio data, typically μ-law or A-law encoded. Standard on Sun/NeXT workstations and early internet audio. Supported for legacy compatibility with Unix systems, Java applications, and archival files from early digital audio era.

MID

Musical Instrument Digital Interface - not actual audio but musical notation data specifying notes, timing, instruments, and performance parameters. Extremely small files (kilobytes for entire songs). Playback quality depends on sound bank (synthesizer quality). Standard for music composition, karaoke, educational music software, and embedded systems. Essential format for music notation and algorithmic composition.

RealAudio - pioneering streaming audio format from RealNetworks (1995), enabling internet audio streaming on dial-up connections. Highly compressed for low-bandwidth delivery (8-96kbps). Revolutionary in 1990s internet but obsoleted by modern codecs (MP3, AAC, Opus). Historical format maintained for accessing archived internet radio content and legacy streaming media from early web era.

Specialized Encodings

DTS

Digital Theater Systems - high-quality multi-channel audio codec competing with Dolby Digital. Superior quality at equivalent bitrates with support for up to 7.1 channels. Standard on many Blu-rays and in home theater systems. Higher bitrates (768kbps-1.5Mbps) than Dolby Digital. Professional format for cinema sound and premium home entertainment. Essential for audiophile home theaters and high-end audio systems.

CAF

Core Audio Format - Apple's professional audio container supporting any codec (PCM, AAC, ALAC, etc.) with flexible metadata and 64-bit file sizes. Designed for audio production, sound design, and applications requiring features beyond standard formats. Native support in macOS audio applications. Handles extremely long recordings and high sample rates. Ideal for iOS/macOS audio development and professional Mac-based audio workflows.

VOC

Creative Voice File - format from Creative Labs' Sound Blaster cards (1989), standard in DOS-era PC gaming. Simple compressed format for 8-bit sound effects and voice. Nostalgic format from golden age of PC gaming (Doom, Duke Nukem 3D). Maintained for retro gaming, sound effect libraries, and accessing audio from vintage PC games and multimedia applications.

SPX

Speex - specialized open-source codec optimized exclusively for speech at low bitrates (2.15-44kbps). Excellent quality for voice at tiny file sizes. Includes voice activity detection and noise suppression. Designed for VoIP, voice messaging, and audio books. Largely superseded by Opus (which includes speech optimization) but still used in legacy VoIP systems and embedded applications requiring minimal resources.

DSS

Digital Speech Standard - proprietary format from Olympus and Philips for dictation and voice recording devices. Highly compressed (12-16kbps) with acceptable speech intelligibility. Includes metadata for dictation workflow (author, priority, annotations). Standard in legal, medical, and business dictation systems. Specialized format for professional transcription services and dictation equipment.