OPUS Compressor

Compress OPUS Audio Online

Opus is already one of the most efficient audio codecs in existence, so most .opus files are small to begin with — there is far less to squeeze out than from a WAV or a 320 kbps MP3. Compressing an Opus file means re-encoding it at a lower bitrate, which costs you a generation of quality because the source is already lossy (lossy in, lossy out). Reach for this when you have to clear a hard upload or attachment cap, or to shrink long voice notes and call recordings where a little quality loss is acceptable. Files are uploaded over an encrypted connection, processed on our servers, and deleted automatically a few hours after conversion — no sign-up, no watermark, never shared or made public.

How to Compress an OPUS File

1. Upload Your OPUS File: Drag and drop your .opus track or click "Add Files" to browse. Batch uploads are supported, so you can shrink a whole folder of voice notes in one pass.
2. Pick a Compression Method: Choose Custom Bitrate for an exact target like 32 or 48 kbps, Variable Bitrate to pick an Opus quality band (the dropdown ranges from 6k–24k up to 192k–256k), Specific file size to back-solve the bitrate from an exact MB target, or File Size Percentage to shrink each file to a share of its current size.
3. Adjust Channel, Sample Rate, and Trim (Optional): Switch Audio Channel from Stereo to Mono to roughly halve a two-channel voice file, drop Audio Sample Rate for speech-only material (Opus handles 8–48 kHz), or use Trim to cut dead air before re-encoding — trimming often saves more than lowering the bitrate.
4. Compress and Download: Click "Compress" and grab each file individually or as a ZIP. No sign-up, no watermark, no email gating.

Opus Bitrate Guide — Pick by Content Type

Opus picks its internal mode automatically — SILK for speech, CELT for music, and a hybrid in between — so the right bitrate depends mostly on what is in the file. Figures below follow Xiph's published recommendations; "size per hour" is the resulting file for one hour of audio.

Below roughly 24 kbps music falls apart, but a single mono voice stays intelligible all the way down toward Opus's 6 kbps floor — that low-bitrate speech range is where Opus genuinely beats older codecs like MP3 and AAC. If your file is already at or below 32 kbps (typical for WhatsApp, Telegram, or Discord voice notes), there is little headroom left; trim the recording or accept that re-encoding will be audible.

Which Compression Method Should You Pick?

The tool exposes five ways to target size. They all drive the same encoder but differ in how you state the goal:

For voice notes, Variable Bitrate at the 24k–40k band with Audio Channel set to Mono is the sweet spot; for a hard cap, use Specific file size and aim a little under the limit to leave room for container overhead.

Frequently Asked Questions

Why does my Opus file barely get smaller when I compress it?

Because Opus is already extremely efficient — most .opus files are encoded near their content's transparency point, around 128 kbps for music and 24–32 kbps for voice. Little redundant data is left to remove, so dropping the bitrate further trades audible quality for only a modest size cut. If the file is already a low-bitrate voice note, the biggest win usually comes from trimming silence with the Audio Cutter, not from re-encoding.

Does compressing an Opus file lose quality?

Yes. Opus is lossy, so re-encoding it at a lower bitrate discards more audio data and stacks a second generation of artefacts on top of the first. For spoken word the loss is often inaudible down to about 24 kbps mono; for music the practical floor is higher — around 96 kbps — before cymbals and reverb tails start to smear. If you still have the original lossless or higher-bitrate source, encode straight from that instead of from the existing Opus.

What bitrate should I use for a voice recording versus music?

For a single mono voice — narration, a lecture, a voice memo — Xiph's clean range is 24–32 kbps, and wideband speech still holds up at 16–24 kbps. For stereo music, stay at 96–128 kbps where Opus is effectively transparent; 64–96 kbps is fine for casual listening. Interviews and group recordings with several speakers sit comfortably at 48–64 kbps. A music bitrate on a voice note just wastes space, and a voice bitrate on music will sound thin.

How do I hit an exact size for an email or Discord upload?

Choose Specific file size and enter your target in MB; the encoder back-solves the bitrate from the clip's duration. This is handy for fitting a long recording under an email attachment limit or a chat app's upload cap — Discord's free tier, for example, is 10 MB. Aim slightly under your target to leave room for container overhead, and remember that switching Audio Channel to Mono on a stereo voice file roughly halves the size before you even touch the bitrate.

Will my compressed Opus file still play everywhere?

Mostly, but not universally. Opus plays natively in Chrome 33+, Firefox 15+, and Edge 14+, and Android has supported it for years; Safari has only partial support across desktop versions, and iOS Safari gained full playback in 18.4. Compressing the file does not change which players accept it — the container and codec stay Opus either way. If a device or app refuses .opus, use Opus to MP3 for the widest compatibility rather than lowering the bitrate.

What is the lowest bitrate an Opus voice note stays understandable at?

Opus is defined for bitrates from 6 kbps up to 510 kbps (RFC 6716). Its SILK speech layer keeps a single mono voice intelligible down toward that 6 kbps floor, which is why Opus is used for real-time calls on constrained connections. Music needs far more headroom and starts breaking up below about 48 kbps. For an archival voice note you want to keep clearly readable, 16–24 kbps mono is a safer target than chasing the absolute minimum.

Should I just convert Opus to MP3 instead of compressing it?

Usually no — Opus is more efficient than MP3 at every bitrate, so converting to MP3 to "save space" makes the file larger for the same quality. Convert to MP3 only for compatibility with a player or device that cannot read .opus. In our testing, re-encoding a 5-minute mono Opus voice note to MP3 at a perceptually matched setting produced a noticeably larger file than the Opus original. If compatibility is the real goal, use Opus to MP3 rather than this compressor.

Are my files private?

Files are uploaded over an encrypted connection, processed on xconvert's servers, and deleted automatically a few hours after conversion. The audio is never shared, never made public, and is not used to train any model — no account or email is required. To shrink a mix of formats in one job, the broader Audio Compressor handles MP3, WAV, M4A, OGG, FLAC, and Opus together.