AudioCalcs
Cartridge Alignment Calculator
Calculate overhang, offset angle and null points for tonearm cartridge alignment.
How We Calculate This
Overhang
Overhang = Effective Length - Mounting Distance — this is simply how far the stylus sits past the spindle for the mounting distance you entered. To actually realise the chosen geometry's offset angle and null points, the mounting distance must satisfy L² = M² + N₁·N₂, so the geometry-consistent mounting distance is M = √(L² − N₁·N₂). If the mounting distance you entered differs from that recommended value, the calculator flags it: your arm will null at different radii than the ones listed until you move the pivot to the recommended distance.
Null Points
The two radii where the stylus tracks the groove tangentially (zero tracking error). They depend only on the chosen inner and outer groove radii of the recorded band — a standard 12-inch LP is 60.325 mm (inner) and 146.05 mm (outer) by the IEC standard — and on the optimisation criterion, not on arm length. For IEC radii: Baerwald (Löfgren A) ≈ 66.0 / 120.9 mm, Löfgren B ≈ 70.3 / 116.6 mm, Stevenson 60.325 / 117.42 mm.
Offset Angle
The angle between the cantilever and a line from the stylus to the pivot. From the null radii N₁, N₂ and the effective length L it is θ = arcsin((N₁ + N₂) / (2 × L)). For a 230 mm Baerwald arm this is arcsin(186.9 / 460) ≈ 24°.
Frequently Asked Questions
Cartridge alignment ensures the stylus traces the record groove at the correct angle, minimising tracking distortion. Poor alignment increases distortion, accelerates record and stylus wear, and degrades sound quality — particularly at the inner grooves where the problem is worst.
Baerwald is the most popular and distributes error evenly — it is the best all-round choice. Loefgren B is slightly better for full-side listening. Stevenson prioritises inner groove accuracy, beneficial for classical records where the crescendo is often near the end of a side.
Null points are the two radii on the record where tracking error is exactly zero. Between and outside these points, there is some tracking angle error. Different geometries place the null points at different positions to optimise different aspects of playback quality.
Use a protractor (alignment gauge) placed on the platter. The stylus is placed on each null point and the cartridge body is rotated until it is parallel to the grid lines. Adjust the cartridge position in the headshell slots to set the correct overhang first, then adjust the angle.
Was this calculator helpful?
Last updated: March 2026
All calculations are estimates based on standard formulas. Always verify results for critical applications.