Vinyl RPM Calculator — Playing Time & Groove Spacing

At 45 RPM the groove velocity is higher, meaning more vinyl passes under the stylus per second. This allows wider groove modulation, better high-frequency response, greater dynamic range and less inner-groove distortion. The trade-off is shorter playing time per side.

As the stylus moves towards the centre of the record, the linear velocity decreases. This means the same audio frequency is encoded in a shorter physical space, making it harder for the stylus to track accurately. On a standard 12-inch LP the innermost groove (radius ≈60 mm) runs at only about 41% of the outermost groove speed (radius ≈146 mm) — a velocity ratio of roughly 2.4:1, so the inner groove is moving at less than half the velocity of the outer groove.

A standard 12-inch LP at 33⅓ RPM can hold about 22 minutes per side with good audio quality. Pushing beyond 25 minutes requires narrower grooves, which reduces volume and bass response. A 12-inch single at 45 RPM typically holds 10-12 minutes per side.

Groove spacing (or pitch) is the distance between adjacent grooves on the record. Wider spacing allows louder cuts with more bass, while narrower spacing fits more playing time. Typical spacing ranges from 0.1mm (long playing) to 0.3mm (loud cuts).