Vinyl Runtime Calculator
Vinyl mastering engineers must balance audio quality against runtime. More music per side means tighter groove pitch, which limits bass level and dynamic range. This calculator estimates maximum playback time per side based on disc diameter, rotation speed, groove pitch (lines per inch), and the usable groove area. The formula computes total groove length as the area swept between inner and outer groove radii divided by groove pitch, then divides by the linear velocity at the average radius. Use this to estimate whether your album will fit at a given groove pitch before cutting.
Vinyl runtime formula
Groove length (inches) = pi * lpi * (R_outer^2 - R_inner^2)
Linear velocity (in/min) = 2 * pi * R_avg * rpm
Runtime (min) = Groove length / Linear velocity
12-inch LP: R_outer = 5.75 in, R_inner = 2.25 in
The usable groove area runs from the outer locked groove to the inner lead-out. For a 12-inch LP, the playable band spans roughly 2.25 inches inner radius to 5.75 inches outer radius. The groove pitch (lpi) determines how many concentric grooves fit in this band.
Vinyl runtime guidelines for mastering
- Under 18 minutes per side: room for loud, wide grooves with full bass and dynamics.
- 18 to 22 minutes: standard LP range, moderate groove pitch.
- 22 to 26 minutes: tight pitch, bass must be reduced and levels lowered.
- Over 26 minutes per side: significant compromises to audio quality required.
- 7-inch 45 at 45 rpm: typically 4 to 6 minutes per side maximum.
Vinyl runtime: frequently asked questions
How long can each side of an LP hold?
A standard 12-inch LP at 33 1/3 rpm can hold approximately 18 to 22 minutes per side at normal groove pitch. The actual limit depends on groove pitch (spacing between grooves), modulation level, and how loud the content is. Louder audio requires wider groove spacing, reducing runtime. Very quiet content can stretch to 25-30 minutes per side.
Why does loud audio reduce vinyl runtime?
Loud audio requires the cutting stylus to cut wider, deeper grooves. Wider grooves take up more space on the disc, which means fewer grooves fit per side, reducing the maximum playback time. This is the primary constraint in vinyl mastering.
How is vinyl runtime calculated?
Runtime (minutes) = usable groove area / (groove pitch * record speed). Groove pitch is typically measured in lines per inch (lpi). At 33 rpm, 100 lpi, and a usable radius from 57 mm to 146 mm, each side holds roughly 22 minutes. This calculator uses standard industry parameters.
What is the difference between 33 rpm and 45 rpm?
45 rpm records spin faster, so each groove passes the stylus more quickly. A 7-inch 45 typically holds 3 to 5 minutes per side. The faster speed gives better high-frequency response and dynamic range but limits runtime.
What groove pitch is standard?
Standard groove pitch for an LP is approximately 90 to 110 lines per inch (lpi). Tighter pitch (more lpi) means more grooves and longer runtime but reduces maximum audio level and bass content.
Official sources
- Audio Engineering Society (AES): aes.org - vinyl mastering and disc recording standards.
- Recording Industry Association of America (RIAA): riaa.com - RIAA equalization and vinyl format history.
Reviewed by the CalculatorHub team, edited by James Graham, 15 June 2026. See our methodology.