What is a swing ratio?

Swing splits a pair of eighth notes — which together fill one beat — into a long on-beat note and a short off-beat note. A ratio of long-to-short parts describes the split: 1:1 is straight, 2:1 is hard triplet swing, and 3:2 is a softer medium swing. The on-beat gets the larger share of the beat.

How does swing ratio relate to swing percentage?

Many DAWs express swing as a percentage where 50 percent is straight and about 66.7 percent is triplet swing. The percentage equals 100 · long / (long + short). So a 2:1 ratio is 66.7 percent and a 3:2 ratio is 60 percent. The calculator shows both.

How are the millisecond offsets computed?

One beat lasts 60000 / BPM ms. The on-beat eighth takes long / (long + short) of that beat and the off-beat takes the remaining short / (long + short). The off-beat shift versus a straight feel is the on-beat duration minus half the beat.

What swing feel should I use for different styles?

Jazz and shuffle blues often use a strong 2:1 triplet swing. Funk, hip-hop and house typically use lighter swing in the 54 to 62 percent range for a subtle push. Straight 50 percent suits most rock and electronic four-on-the-floor. Experiment, because feel is genre and tempo dependent.

Why does the off-beat move later instead of earlier?

Swing delays the off-beat eighth so it lands closer to the next downbeat, lengthening the on-beat note. That late placement of the and creates the characteristic long-short lilt. The calculator reports exactly how many milliseconds later the off-beat sits compared with an even split.

Swing & Groove Timing Calculator

Swing is what separates a stiff, machine-quantized beat from one that breathes. It works by shifting the off-beat eighth notes later, creating a long-short lilt. This calculator turns any swing ratio into the exact millisecond timings you need to dial into a sampler, sequencer or delay.

How it works

A pair of eighth notes together fills one quarter-note beat. Swing divides that beat unevenly between the on-beat (down) eighth and the off-beat (and) eighth, according to a long-to-short ratio. With L long parts and S short parts and a beat of 60000 / BPM milliseconds:

on-beat eighth  = beat · L / (L + S)
off-beat eighth = beat · S / (L + S)
swing percent   = 100 · L / (L + S)

A straight feel is 1:1 (50 percent). Hard triplet swing is 2:1 (66.7 percent), where the off-beat lands on the final triplet of the beat. The off-beat’s shift from a straight placement is the on-beat duration minus half the beat.

Tips and example

At 120 BPM the beat is 500 ms. A 2:1 triplet swing makes the on-beat eighth 333 ms and the off-beat 167 ms, pushing the off-beat 83 ms later than a straight 250 ms split — an unmistakable jazzy bounce. A gentler 3:2 ratio (60 percent) shifts it only 50 ms.

Lighter swing (54–62 percent) adds groove without sounding overtly shuffled.
Match the feel to genre and tempo; fast tempos usually want less swing.
Apply the off-beat shift value directly when nudging notes in a piano roll.

All timing maths runs locally in your browser.