How our free online mastering works
Mastering is the last step before release: it makes your song loud enough to compete, balances its tone and makes sure it translates on every system, from earbuds to car speakers. Our free online mastering does that in four steps:
- Upload your mix. WAV, MP3, FLAC or M4A, up to 15 minutes. A 24-bit WAV gives the best result.
- Pick a style and a loudness. Balanced, Warm or Bright, and Streaming, Standard or Loud.
- Compare before and after. Switch between the original and the master at the same point of the song and check the loudness and peak readings.
- Download your master. A 24-bit WAV, free, with no sign-up and no watermark.
It takes about a minute. If you don't like the result, try another style or loudness: your original stays loaded.
What happens to your song
Behind the progress bar there is a full mastering chain, the same kind of processing an engineer would reach for on a song, applied in this order:
- Level matching. Your mix is brought to a consistent working level first, so a quiet bounce and a hot one get the same treatment.
- Sub-rumble cleanup. A high-pass filter at 30 Hz removes inaudible energy that eats headroom without adding anything you can hear.
- Tonal EQ. Four gentle bands shape lows, low-mids, presence and air. Balanced, Warm and Bright set how far each one moves, never more than a couple of dB.
- Glue compression. A slow, 2:1 compressor ties the elements together without squashing the transients of your drums.
- Mono bass. Everything below 150 Hz is centered, so the kick and the 808 stay solid on phones, club systems and Bluetooth speakers.
- Stereo width. The sides above the bass get a subtle lift for a wider, more open image.
- Loudness and true-peak limiting. The track is raised to the loudness you picked and a limiter with 4× oversampling keeps every peak, including the ones between samples, under −1 dBTP. That is what stops distortion when streaming services convert your file.
- 24-bit render. The master is delivered as a 24-bit WAV with dither, ready to upload or to send to a distributor.
Which loudness should I choose for my song?
Loudness is measured in LUFS, and it matters because every streaming platform turns songs up or down to a common level:
- Spotify and YouTube normalize to around −14 LUFS. Spotify also recommends keeping true peaks under −1 dBTP, which is exactly where our limiter sits.
- Apple Music uses Sound Check, which plays songs at around −16 LUFS.
So a master at −14 LUFS keeps all its dynamics on streaming, while a louder one gets turned down and can sound flatter next to it. That's why we offer three targets:
- Streaming (−14 LUFS) for singer-songwriter, R&B, acoustic and anything that lives on dynamics.
- Standard (−11 LUFS) for most rap, pop and hip hop. A good default.
- Loud (−9 LUFS) for trap, drill and club records, where the energy of a loud master is part of the genre.
Not sure? Master it twice and compare. Our guide on how to master a song goes deeper into loudness and streaming.
How to prepare your mix for mastering
A master can only be as good as the mix it starts from. Before you upload:
- Leave headroom. Your loudest peaks should sit around −6 to −3 dBFS. If the meter on your master bus is hitting 0, turn the mix down, not the tracks one by one.
- Take the limiter off the master bus. A limiter or maximizer on your mix leaves the mastering chain nothing to work with. Bus compression is fine if you like how it sounds.
- Export a WAV. 24-bit (or 32-bit float) at the sample rate of your session. MP3 works, but it has already thrown away detail.
- Check the vocal balance. Mastering moves the whole song at once: it can't bring up a buried vocal on its own.
- Compare with a reference. Listen to a released song you like at the same volume. Our post on how to use reference tracks explains how.
If the mix itself needs work, start with how to improve the mixdown and mastering of your music.
Free mastering vs. professional mix and master
Both have their place. Here is the honest difference:
| Free mastering | Professional, by hand | |
|---|---|---|
| How it works | An automatic mastering chain with your choice of style and loudness | Our engineers mix and master your song by ear |
| What you send | Your finished stereo mix | The stems of the beat and your vocals |
| Fixes the mix | No: it polishes the mix you upload | Yes: levels, vocals, low end and effects are rebalanced |
| Best for | Demos, snippets, testing ideas and songs that are already well mixed | Releases where the song has to stand next to the records you love |
| Price | Free | Song Mixdown & Master, paid per song |
Frequently asked questions
Is the online mastering really free?
Yes. You can master as many songs as you want and download each one as a 24-bit WAV. There is no sign-up, no watermark and no trial.
Do you keep or share my song?
No. Your audio is never stored on our servers and nobody else listens to it. Close the page and it is gone.
Can I release the master on Spotify and Apple Music?
Yes. The master is yours: upload it to your distributor like any other file. If your song uses a leased beat, the release terms are the ones in your beat license.
Which file formats can I upload?
WAV, MP3, FLAC and M4A, up to 15 minutes. For the best result, export a 24-bit WAV at the sample rate of your session.
How long does it take?
About a minute per song. You can watch every step of the chain while it works.
Why doesn’t my master sound like a commercial record?
Most of the sound of a record comes from the mix and the recording, not from mastering. If the vocal sits wrong or the low end is muddy, mastering makes it louder, but the problem is still there. That is what our professional mix and master is for.
Which style should I pick?
Balanced suits most songs. Warm adds weight to the lows and softens the top, great for bright or harsh mixes. Bright adds presence and air, great for dull or dark mixes. Compare them: it takes a minute.
Can I mix and master my song online for free?
The free tool masters a finished stereo mix. Mixing is a different job: it needs the separate tracks (the stems of the beat and your vocals) and someone balancing them by ear. That is what our paid Song Mixdown & Master is for.