Free tools for common watchmaking calculations.
Enter barrel and arbor measurements, get recommended mainspring thickness, length, and height. Dennison/Grossmann formula with rule-of-thirds visualization.
Convert between ligne, millimeters, inches, and mils. Thread reference tables for Swiss TAP, metric, and BA screws.
Convert between American sizes (0s–18s), millimeters, and ligne. Shows movement plate and typical case diameter.
