What Happens When You Slow a Song Down
Tempo and pitch are stored together in a normal audio file, so playing that file more slowly lowers the pitch too — the same effect as slowing a record by hand. The vocals drop in key, instruments sound heavier, and a 3-minute track gets longer. Modern tools break the two apart. By stretching the audio without resampling it, they can hold the original pitch while only the tempo changes. That is what you want for practice and transcription; the lowered pitch is what you want for a slowed edit.
How to Slow Down a Song Without Changing the Pitch
- Open a browser-based slowdown tool, such as Song Slower, and upload your file.
- Drag the speed slider below 100% (drag it left, toward 0.5x).
- Leave the pitch switch off. Only the tempo changes; the key stays where it was.
- Preview the result and adjust the speed in small steps.
- Export as MP3 or WAV.
How Much Slower Should You Go?
| Speed | What it's good for |
|---|---|
| 95%–90% | Barely noticeable — fitting a track to a video or a spoken segment |
| 85%–80% | The classic slowed feel; most edits live here |
| 75%–70% | Heavier, more obviously slowed; solos become easy to follow |
| 60%–50% | Extreme — artefacts and smeared transients may become more noticeable |
Below roughly 60% stretching artefacts can become more noticeable, so 80%–90% is a useful starting range for many tracks.
Slowing Down vs Lowering the Pitch
These are separate controls, and mixing them up is the most common mistake.
- Slower, same key: pitch stays put, tempo drops. Use it for practice, karaoke backing tracks, transcription and language learning.
- Slower and lower: pitch drops with the tempo (usually 2–4 semitones). This is the sound behind most slowed edits.
- Same speed, lower pitch: the tempo doesn't move; the key does. Useful for fitting a vocal to a different backing track.
How to Get the Slowed + Reverb Sound
Three settings do all of it:
- Speed around 87% — slow enough to change the feel without losing the song's shape.
- Reverb mix around 35% — a long, roomy tail behind the vocal.
- Pitch down 3 semitones — the darker, heavier tone the style is known for.
Our Slowed + Reverb Generator applies all three as a one-click preset, and each can be adjusted afterwards.
Common Mistakes
- Going too slow. Under 70% vocals can smear and the track may start to drag.
- Too much reverb. Past 50% words can become harder to follow; ease the mix back before adding more.
- Changing both controls at once. Set the speed first, listen, then add reverb.
- Re-encoding twice. Export to WAV if you plan to edit again, and to MP3 only for the final file.
Check the Result Against Your Goal
For practice or transcription, preview with reverb off and pitch unchanged. Listen to the note attacks or consonants you need to hear, then compare the same phrase at normal speed. For a creative edit, test the busiest section as well as the intro. Tempo and pitch processing can affect different recordings differently, so do not judge quality from the percentage alone. Keep the original and make each new version from it.
A slower file is longer: divide its original duration by the speed as a decimal. A three-minute source at 75% lasts approximately four minutes before any added effect tail. This helps you plan a practice file or a video sequence, but the tool does not automatically trim the export to your project duration. If you instead need a faster version, the Nightcore Maker offers the reverse speed range.
File Formats and Device Limits
Use MP3 at 320 kbps for a finished file, or 16-bit PCM WAV when another editing step follows. WAV avoids another lossy compression step but cannot recreate detail that was absent from the source. Inputs in MP3, WAV, M4A, FLAC, and OGG have been tested in Chromium. Other browsers may decode different formats or codecs. Try a short local file first if you are unsure about a phone or tablet.
Song Slower accepts files up to 200 MB and has no separate duration cap. Processing still needs enough browser memory for decoded audio and the longer result. Keep the tab open while the file is being processed; downloaded files remain on your device afterward. If a long recording cannot finish, prepare a shorter excerpt in an editor instead of repeatedly loading the same large file.