From 128 to 140 — what does it cost?
Type both tempos and see the move: the stretch percentage, how many semitones a pitch-ride drifts, and whether the halftime or doubletime door is the smarter way in.
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| Path | Stretch | Pitch-ride drift | Verdict |
|---|
The math says what's possible. The console makes it seamless.
SongRemixer warps tracks to each other with pitch and tempo decoupled — the transition this calculator plans, executed. Sign up: 3 full packs free.
The 6%-per-semitone rule of thumb
Tempo and pitch are the same knob on any keylock-off system: a 6% speed change is almost exactly one semitone. That single number turns transition planning into arithmetic — 128 to 135 is +5.5%, so a pitch-ride costs just under a semitone; 128 to 150 is +17%, which no keylock rescues gracefully, so you look for the halftime door or a hard cut instead.
The table's verdicts encode the working thresholds: under 4% is invisible, under 8% is club-normal, past 10% plan something cleverer than a long blend.
Frequently asked questions
How much can I stretch a track before it sounds wrong?
On keylock (master tempo), ±4% is invisible, ±8% is club-acceptable, and past ±10% transients start to smear. Without keylock the limit is pitch: every 6% of tempo is about a semitone of drift, and one full semitone is where most ears notice a sung vocal.
What's the halftime/doubletime trick?
A 70 BPM hip-hop groove and a 140 BPM drum-and-bass groove share a pulse — one is the other felt twice as fast. When the direct stretch between two tempos is too big, check whether halving or doubling one side brings the gap under a few percent; the calculator shows both paths.
Should I match BPM exactly or ride the pitch fader?
Digital DJs sync exactly and keep keylock on. Vinyl and pitch-ride DJs trade a little key drift for feel — which is fine, as long as you know how many semitones you're trading. That's the number this tool puts in front of you.
Why does the calculator show a semitone value?
Because tempo and pitch are locked together on turntables and keylock-off players: speed a record up 6% and it plays about a semitone sharp. Knowing the drift tells you whether the blend will still sit in a compatible key.