Pitch & Tempo Changer + Song Slow-Downer — No Upload
Pitch & Tempo
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Change the pitch of a song without touching its speed — or slow it down without dropping the key. The two sliders are independent: that’s the whole trick, and it happens entirely in your browser. Nothing is uploaded, no account, no queue — drop a file, turn the knobs, hear it live, download the result as WAV, MP3 or M4A.
Slow down a song to learn it
The practice workflow, the one guitar players and pianists actually come for:
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Drop the song (or pick one of ours to try the tool first).
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Hit a practice speed — 75% is the sweet spot for learning a solo, 50% for transcribing the truly cursed runs.
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The pitch stays put — slowing down does NOT detune the track, so you can play along in the original key the whole time.
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Work the speed back up: 75 → 85 → 100. Muscle memory likes the ladder.
Old tape machines and vinyl couldn’t do this — slower always meant lower. Decoupling time from pitch takes actual signal surgery (time-stretching), and that’s what runs under the hood here.
Change the key, keep the speed
The other direction: transpose a song without making it faster or slower.
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A singer needs the track 2 semitones down — done, the tempo doesn’t move.
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Your cover sits better a semitone up — slide +1 st and the groove stays exactly where it was.
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Fine-tuning lives in the cents box: a track recorded at A=432 Hz is about −32 cents off standard A=440 — nudge it back without touching anything else.
Pitch is limited to ±12 semitones — one octave each way. Beyond that nobody’s asking for music anymore, they’re asking for sound design.
Semitones ↔ percent
When you DO want the coupled, tape-style behaviour (pitch and speed moving together), set both sliders by the same factor. The conversion — one semitone is ×21/12 ≈ 5.95%:
| Shift | Factor | As a percent |
|---|---|---|
+12 st |
×2.000 |
+100% |
+7 st |
×1.498 |
+49.8% |
+5 st |
×1.335 |
+33.5% |
+3 st |
×1.189 |
+18.9% |
+1 st |
×1.059 |
+5.9% |
−1 st |
×0.944 |
−5.6% |
−3 st |
×0.841 |
−15.9% |
−5 st |
×0.749 |
−25.1% |
−7 st |
×0.667 |
−33.3% |
−12 st |
×0.500 |
−50% |
Classic party trick from the table: vinyl cut for 45 RPM played at 33⅓ runs at ×0.74 — about −5.2 semitones. Now you know why slowed + reverb edits all sit in that murky lowered-key zone.
Honest about artifacts
Time-stretching is surgery, and surgery leaves scars. Moderate moves (tempo 75–125%, pitch within ±5 st) sound clean on most material. At the extremes — 20% tempo, ±12 st — expect smearing and a watery texture, especially on vocals and dense mixes: the algorithm (WSOLA time-domain stretching) has to invent or discard a lot of waveform, and there is no free lunch in DSP. Drums survive best, solo voice complains first. The preview is live — if it sounds wrong, you’ll know before you download.
Made by a band, for people who make music. While you’re here — have a listen to ours. Need the song’s tempo first? The BPM finder draws the whole tempo curve; and a finished mix can go straight through the mastering tool.
Frequently Asked Questions
Does slowing a song down change its pitch?
No — that's the whole point of this tool. Tempo and pitch are processed independently: slow a track to 75% and it stays in the original key, so you can practice along without retuning your instrument. (If you WANT the coupled tape-style drop, set both sliders by the same factor — the semitones↔percent table on this page does the math.)
Is my file uploaded anywhere?
No. Decoding, the live preview and the final render all run in your browser — the file never leaves your device, there's no account and no queue.
How far can I shift the pitch?
±12 semitones (an octave each way), plus a cents box for fine moves like the A=432 Hz → A=440 correction (about 32 cents). Honest warning: beyond roughly ±5 semitones vocals start sounding processed — that's physics of time-stretching, not a bug to fix in settings.
Why does an extreme setting sound watery or smeared?
Time-stretching has to invent waveform (when slowing) or throw it away (when speeding up). At moderate settings the seams are inaudible; at 20% tempo or ±12 semitones they're the dominant texture, especially on voice and dense mixes. Drums tolerate it best. The live preview tells you honestly what you'll get before you download.
Is the downloaded file the same quality as the preview?
Same engine, better path: the download is rendered offline from the original decoded audio at its native sample rate — it is NOT a recording of the preview stream. WAV is lossless 24-bit; MP3 (320 kbps) and M4A (AAC 256 kbps) are encoded from that render.
Which formats can I open?
WAV, MP3, M4A/AAC, FLAC and OGG — anything your browser can decode, plus a built-in fallback decoder for the exotic cases.
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