Fret Metric calculates the ideal string action height for every string on your guitar. Simply measure the action at your 1st and last strings at the 12th fret, and the app calculates the target height for all strings in between. FEATURES - Radius-based calculation that accounts for your fretboard's actual curvature - Linear calculation mode for quick approximations - Support for 4, 6, 7, 8, and 12-string guitars - Common fretboard radius presets (7.25", 9.5", 10", 12", 14", 15", 16", 20") - Custom radius input for non-standard fretboards - Nut width configuration for precise geometry - Works in millimeters or inches - Real-time results as you adjust measurements - Built-in guide with measurement instructions and reference setups - Dark mode support - All settings saved automatically Whether you're a guitarist fine-tuning your setup or a luthier working on a client's instrument, Fret Metric gives you the precise measurements you need.