What Format to Send for Mastering
Published · updated · by Loopin
Send a WAV or AIFF (lossless), 24-bit, at your project sample rate (44.1 kHz for music), with headroom — peaks around −6 dB — and no limiter or maximizer and no dither on the mix bus, with no clipping. Don’t send an MP3, and name the file clearly. That gives the mastering stage the room it needs to work.
The format at a glance
Every requirement here exists for one reason: to hand the mastering stage a clean, full-resolution file with room to work. Get these right and the master has everything it needs.
Here’s the whole checklist in one place before we unpack each part.
- WAV or AIFF — lossless, never MP3.
- 24-bit depth for full dynamic range.
- Project sample rate — 44.1 kHz for music.
- Headroom — peaks around −6 dB.
- No limiter or maximizer on the mix bus.
- No dither on the mix bounce.
- No clipping anywhere.
- Name it clearly.
WAV or AIFF, never MP3
Send a lossless file — a WAV or an AIFF. Both preserve every bit of your mix exactly as it left your DAW, which is what the mastering stage needs to work on.
An MP3 is lossy: it throws away audio data to shrink the file, and it bakes in compression artefacts that mastering can’t undo. Mastering an MP3 means processing damage that’s already there. So don’t send an MP3 — export a WAV or AIFF instead.
- WAV — the most universal lossless format.
- AIFF — equally lossless, common on Apple systems.
- Not MP3 — lossy files bake in artefacts mastering can’t fix.
24-bit, at the project sample rate
Export at 24-bit. That depth gives you generous dynamic range, so you can leave headroom without any noise penalty — exactly what the master stage wants to see.
Keep the file at your project sample rate — 44.1 kHz for music. Don’t convert to a different rate just to hand it off; deliver at the rate you recorded and mixed in so nothing gets resampled unnecessarily.
- 24-bit — full resolution, room to leave headroom.
- Project sample rate — 44.1 kHz for music; don’t resample to hand off.
- Sample rate and bit depth are separate settings — set both.
Leave headroom — peaks around −6 dB
Bounce the mix with headroom: peaks around −6 dB below 0 dBFS. That empty space at the top is what the mastering chain uses to shape tone and set loudness cleanly.
If you hand over a file that’s already at the ceiling, there’s nowhere for the processing to move — boosts, compression and saturation all need somewhere to go. Around −6 dB gives the whole chain room to breathe, with no clipping anywhere in the file.
- Aim for peaks around −6 dB — clear space below 0 dBFS.
- No clipping anywhere — check your peak meter before export.
- Don’t normalize the bounce to 0 dBFS — that eats your headroom.
No limiter, no dither, no clipping — and name it clearly
Take any limiter or maximizer off the mix bus before you bounce. Those tools flatten your peaks and eat your headroom, and they force mastering to fight processing that’s already been done — two rounds of limiting almost always sound worse than one. Leave dither off the mix bounce too: dither belongs at the very last step, when the finished master is converted to its final bit depth — not on the file you hand to mastering.
Then check the whole file for clipping before you send it. A single clipped section is distortion that’s already baked in, and no amount of mastering removes it — run the mix through and watch the peak meter never touch 0 dBFS. Finally, name the file clearly: the song title, and the rate and depth if you like, so the right file gets mastered and nothing gets confused with a rough bounce or an old version.
- Remove any limiter or maximizer from the master fader.
- No dither on the mix bounce — it belongs at the final export.
- Scan for clipping — peaks must stay below 0 dBFS throughout.
- Name the file with the song title so it’s unmistakable, not an old bounce.
Common mistakes when sending a mix
Most bad handoffs come from a mix that was exported like a finished product rather than a starting point. The usual culprits:
Each of these takes something away from the mastering stage — and every one is easy to avoid once you know the checklist.
- Sending an MP3 — lossy artefacts get baked in; export WAV or AIFF instead.
- Leaving a mix-bus limiter on — it eats headroom and forces double limiting.
- Adding dither too early — save it for the final master export.
- Bouncing at 0 dBFS with no headroom — aim for peaks around −6 dB.
- Ignoring clipping — baked-in distortion can’t be undone.
Step by step: export the right file, then master
Here’s the export checklist, start to finish:
- Set the project to 24-bit at your project sample rate (44.1 kHz for music).
- Take any limiter or maximizer off the mix bus and turn dither off.
- Bounce a WAV or AIFF with peaks around −6 dB and confirm there’s no clipping.
- Name it clearly with the song title.
- Drop the file into Loopin’s free online mastering — it runs entirely in your browser, nothing uploaded.
- A/B Original vs Mastered, confirm it lands near −14 LUFS with true peak at −1 dBTP, then download the WAV.
Hand over a clean file and let mastering work
The right file to send is simple: a clearly named, lossless 24-bit WAV or AIFF at your project sample rate, with peaks around −6 dB, no mix-bus limiter or maximizer, no dither, and no clipping. That’s a file with room to work — not one that’s already been squeezed dry.
Once your mix is that clean file, let Loopin’s online mastering take it the rest of the way — a full chain with loudness targeting to about −14 LUFS and a −1 dBTP ceiling, free, no signup, no watermark, and nothing ever leaves your device.
Frequently asked questions
What file format should I send for mastering?
Send a lossless WAV or AIFF, 24-bit, at your project sample rate (44.1 kHz for music), with peaks around −6 dB, no limiter or maximizer on the mix bus, no dither, and no clipping. Never send an MP3.
Can I send an MP3 for mastering?
No. MP3 is lossy — it discards audio data and bakes in compression artefacts that mastering can’t undo. Always export a lossless WAV or AIFF so the mastering stage works on your full mix.
Should I put a limiter on my mix before sending it for mastering?
No. Take any limiter or maximizer off the mix bus before you bounce. They flatten peaks and eat headroom, forcing the master to fight already-processed audio. Leave loudness for the mastering stage.
Do I add dither when I export my mix for mastering?
No. Leave dither off the mix bounce — it belongs at the very last step, when the finished master is converted to its final bit depth. Adding it early just bakes noise into a file that still has processing ahead of it.
What sample rate and bit depth should the file be?
24-bit at your project sample rate — 44.1 kHz for music. Keep the file at the rate you recorded and mixed in rather than resampling just to hand it off, and deliver 24-bit for full dynamic range.