Reassigning F Lock Functions: Customize Function Keys with Software

F Lock vs. Fn Key: Key Differences Explained

What each key does

• Fn (Function) key: A modifier key (held down) that lets a single physical key send an alternate function — usually hardware or multimedia controls (volume, brightness, play/pause) printed in a secondary color. Common on laptops and compact keyboards to save space.
• F Lock (Function Lock) key: A toggle key that switches the top-row keys between two modes: traditional F1–F12 behavior and the alternate multimedia/system controls. Acts like Caps Lock for the function row.

How they behave differently

• Modifier vs. toggle
  • Fn requires being held with another key to access the alternate action.
  • F Lock toggles the default behavior of the entire F-row until you press it again.
• State persistence
  • Fn has no persistent state — it only applies while pressed.
  • F Lock can persist across keypresses; on some keyboards it resets after reboot, on others it remains until changed.
• Location and indicators
  • Fn is usually at the lower-left of the keyboard (near Ctrl/Alt); it rarely has an LED.
  • F Lock is typically in the function-key row and may include an LED or on-screen indicator showing its state.
• Who implements them
  • Fn behavior is implemented in keyboard firmware/keyboard controller and sometimes handled by system drivers.
  • F Lock is a hardware toggle implemented by the keyboard; some manufacturers expose F Lock settings in software/BIOS.

Typical usage examples

• Laptop: Hold Fn + F5 to lower brightness (Fn as modifier). Press F Lock once to make F5 send the F5 key by default (e.g., Refresh in a browser) without holding Fn.
• External multimedia keyboard