Drop in almost any audio file and get a 44.1 kHz WAV back — the rate music is distributed at. No signup, no watermark, no limit on how many.
44.1 kHz means 44,100 samples of the waveform every second. It is the rate the compact disc used, and the odd-looking number is an accident of history: early digital masters were stored on video tape, and 44,100 was what fitted the line and frame structure of the tape formats in use. Four decades later it is still what music is distributed at — CDs, Spotify, Apple Music, Bandcamp, and every mastering house's default deliverable.
Use it when music is going out into the world: a master for a streaming distributor, a track for a CD run, a submission to a label or a sync library. Use it when a project was recorded at 48 kHz for video and the audio now has a second life as a release. And use it when everything else in a session is 44.1 kHz and one stray file is not — matching the session is nearly always easier than converting the session.
Going down from 48 kHz is the more delicate direction, and it is worth knowing why. The two rates are not a whole-number ratio: 48,000 to 44,100 is 160 to 147, so the resampler cannot just drop samples — it has to reconstruct the waveform and measure it again on a new grid. A good resampler does this without leaving a trace; a careless one folds the frequencies it should have removed back down into the audible range as a thin, glassy edge on cymbals and sibilants. This page uses ffmpeg's resampler, which is one of the good ones.
Do not round-trip. Converting 44.1 to 48 for an edit and then back to 44.1 for release runs the file through two interpolations to arrive where it started, and each one is a small approximation. If your original recording is 48 kHz, convert that original once, directly, to 44.1 — not the 44.1 copy you made earlier, and not a copy of a copy.
You get a WAV at 44.1 kHz. That is deliberate: this page changes one thing, and encoding into MP3 or AAC on the way out would put a lossy re-encode in front of whatever mastering or distribution step comes next — which is exactly the step that wants an untouched file. Convert to a delivery format afterwards, as its own visible step.
Because the first digital masters were stored on video tape, and 44,100 samples per second was what fit its line and frame structure. The number survived into the compact disc standard and from there into everything that followed it.
Yes, and one is what you want. Convert the 48 kHz original directly to 44.1 kHz. Do not convert an intermediate file you already resampled once — each pass is another approximation for no benefit.
Anything above 22.05 kHz is discarded, which is above the range of human hearing and is not the part to worry about. The real risk is a poor resampler leaving aliasing behind, which is audible as a glassy edge on cymbals and sibilants. That is a question about the tool, not about the rate.
A WAV at 44.1 kHz. At 16-bit stereo that is about 10.6 MB a minute, so a four-minute track is around 42 MB. Convert it to a delivery format afterwards if you need one.
Any of MP3, WAV, FLAC, OGG, AAC, M4A, WMA, Opus and AIFF, up to 200 MB per file.