The short version
- Drop in a song, press Preview, drag the Speed slider. From 25% to 200%, and the pitch stays exactly where it was.
- Learning a part? Start at 75%, get it clean three times in a row, then add 5%. Repeat until you’re at 100% (or showing off at 110%).
- Loop the tricky bit with Set A and Set B, and it goes round until it’s in your fingers.
- Need an exact BPM? Type (or tap) the song’s BPM, type the one you want, and it sets the speed for you.
- Download a WAV of the whole song or just the loop. Your file never leaves your device.
How to slow down a song without changing the pitch
- Drop an audio file onto the box or press “Choose a file”. No song handy? Press “Try the demo loop”.
- Press Preview (or the space bar), then pick a preset. “Practice 75%” is a good start.
- Drag the Speed slider or use − and + for 5% steps. It changes live, and the key never moves.
- Loop the hard bit: press Set A at the start of it and Set B at the end. Press ⏮ to jump back to A at any time.
- Optional: move Transpose to put it in your key, or to match a guitar tuned down a half step.
- Press “Download WAV” for the whole song, or “Download just the loop” for a practice file.
Keyboard shortcuts for practising with your hands full: Space play/pause, A and B set the loop, L loop on/off, − + speed, ← → skip 5 seconds. Yes, you can press them with your nose. I’ve tried.
The practice speed ladder
The fastest way to learn something fast is to learn it slow. Your fingers memorise exactly what you repeat, mistakes included, so the trick is to repeat it right. This is the ladder I use:
| Speed | Goal | Move on when |
|---|---|---|
| 50–65% | Work out the notes and the fingering | You can play it without stopping |
| 75% | Clean and in time with the track | Three clean runs in a row |
| 85% | Relaxed hands, no tension | Three clean runs in a row |
| 90–95% | The feel and the dynamics | It sounds like music, not homework |
| 100% | The real thing | You’re grinning |
| 105–110% | Overlearning, so 100% feels easy on stage | Whenever you like |
Pair it with the metronome’s speed trainer once you know the part, so you can practise it without the record too.
How slow can you go?
Time-stretching invents a little time that wasn’t in the recording, so the further you stretch, the more you hear it. Here’s an honest guide:
| Speed | Sounds like | Good for |
|---|---|---|
| 90–110% | Practically the original | Releases, DJ mixes, matching a BPM |
| 75–90% | Clean, slight softening on drums | Practising, play-along, covers |
| 50–75% | A little watery on reverb and cymbals | Learning parts, transcribing |
| 25–50% | Noticeably smeary, notes still clear | Working out very fast runs |
| 125–200% | Choppy above 150% | Podcasts, voice notes, skimming |
Change a song to an exact BPM
The speed you need is the new BPM divided by the old BPM. 120 BPM down to 100 BPM is 100 ÷ 120 = 83%. The BPM calculator in the tool does the maths: type or tap the song’s tempo, type the one you want, and press “Set speed to this BPM”. Don’t know the tempo? The BPM & key finder can work it out from the file.
| Speed | New BPM | New length |
|---|---|---|
| 50% | 60 | 6:00 |
| 75% | 90 | 4:00 |
| 83% | 100 | 3:37 |
| 90% | 108 | 3:20 |
| 110% | 132 | 2:44 |
| 125% | 150 | 2:24 |
| Tool | Speed | Pitch | Best for |
|---|---|---|---|
| Tempo changer (this page) | Changes | Stays the same | Learning, transcribing, hitting a BPM |
| Pitch shifter | Stays the same | Changes | Singing in your key, matching a key |
| Slowed + reverb | Slower | Lower | The dreamy 3 a.m. version |
| Sped up / nightcore | Faster | Higher | The TikTok version |
Tempo-matching your Suno songs
Suno doesn’t always land on the tempo you asked for. If you’re cutting a Vidmuse video to a beat, mixing two tracks together or want your song to sit at an exact BPM for a playlist, find its tempo with the BPM & key finder, then set the exact target here. A nudge of 3–5% is inaudible to almost everyone.
And if you’re learning to play your own AI song on a real instrument (highly recommended, it’s weirdly satisfying), slow it down here and loop the chorus. To get a tempo you can actually play from the start, put it in the style line:
Laid-back indie folk, 88 BPM, steady groove, simple strummed acoustic guitar, warm bass, brushed drums, clear relaxed vocal, easy-to-play chords, cosy, nostalgic
Why I built this
I’m a guitarist: a Cort, a lot of enthusiasm, roughly twelve notes. Every guitar solo I’ve ever wanted to learn was played by someone who was clearly in a hurry. Slowing a song down the old way, like a record, drops it into a different key, so you learn it wrong and then have to unlearn it. Not ideal for someone with twelve notes.
So this keeps the key exactly where it was, loops the bit you’re stuck on, and runs in your browser with no upload. The “Show-off 110%” preset exists because practising slightly faster than the record is the best trick I know. The “Speed run 125%” preset exists because my kids send very long voice notes.
How it works, and what it does with your file
Your browser decodes the file with the Web Audio API. The tempo changer cuts the audio into overlapping slices about 48 ms long and lays them down closer together (faster) or further apart (slower) without changing what’s inside them, so the pitch stays put. Before placing each slice it searches a few milliseconds either side for the spot whose waveform lines up best with the previous one (a method called WSOLA), which is what keeps it smooth instead of stuttery.
The live preview runs in an audio worklet, so the sliders and the loop respond instantly. The download runs the exact same code, checks for clipping and saves a 16-bit WAV. Nothing is uploaded, there’s no account, and the page makes no network requests while it works.
Tempo changer FAQ
How do I slow down a song without changing the pitch?
Open the song in the tempo changer, press Preview and drag the Speed slider below 100%. The song gets slower but stays in the same key, because the audio is time-stretched rather than played slower like a record. Press Download WAV to keep it.
What speed should I use to learn a song?
Start at the speed where you can play it cleanly three times in a row, often 60–75%, then go up 5% at a time. Practising slowly and correctly beats practising fast and sloppily: your fingers learn whatever you repeat.
How do I loop one part of a song?
Play to the start of the tricky bit and press Set A (or the A key), let it play to the end and press Set B. It loops between them until you press Loop again. You can download just the loop as a WAV, too.
How do I change a song to a specific BPM?
Type the song’s BPM (or tap along with the Tap button), type the BPM you want, and press “Set speed to this BPM”. Behind the scenes it’s new BPM ÷ old BPM: 120 BPM to 100 BPM is 83% speed.
Why does it sound a bit watery when it’s really slow?
Stretching audio means inventing time that wasn’t there, so below about 60% you’ll hear a slight smear or flutter, especially on drums and reverb. For learning notes it doesn’t matter. For a finished release, stay between about 80% and 125%.
Can I change the key as well?
Yes. The Transpose slider moves the pitch by semitones without changing the speed, so you can slow a song down and put it in your key at the same time. For key changes on their own, the pitch shifter has a key and capo helper.
What is the difference between this and slowed + reverb?
Slowed + reverb works like a record at the wrong speed, so slowing it also lowers the pitch, which is the whole point of that sound. The tempo changer keeps the pitch exactly where it was, which is what you want for practising and transcribing.
Does this upload my song anywhere?
No. The file is decoded and processed in your browser and the WAV is created on your device. Nothing is uploaded, there’s no account and there’s no watermark.
What file formats work?
MP3 and WAV work in every browser. M4A, AAC, FLAC and OGG work in most. The download is a 16-bit WAV.
Make a song you actually want to learn
The free Paddy Prompt Studio builds Suno style prompts and Vidmuse video scripts. Pick a genre, mood, vocal and tempo, and it writes the style line for you.
Open the Prompt Studio →