How to Toggle Fn Keys on Windows 10 With Fn Lock

To toggle Fn keys on Windows 10, use the Fn Lock shortcut supported by your laptop, or change the keyboard behavior in its BIOS or UEFI setup. Windows does not provide one universal Fn Lock switch: the key combination and the default behavior depend on the computer or keyboard. On many Dell models, for example, Fn + Esc toggles Fn Lock; some HP models use Fn + left Shift. Check your model’s manual before trying a shortcut.

What Fn Lock changes

Keys from F1 through F12 can each have a standard function and a second action shown by a printed icon, such as changing volume, screen brightness, or keyboard lighting. Which action runs when you press a key by itself is set by the keyboard’s design and firmware. On one laptop, pressing F2 may lower the volume; on another, it may send the standard F2 command to an app.

The Fn key is usually a momentary modifier: hold it while pressing a second key to call that key’s alternate action. Fn Lock changes the default for the top row until you toggle it back. This is different from holding Fn down for a single keypress. Dell and HP describe both function-key and action-key behavior in their keyboard documentation and Fn key guide.

Toggle Fn Lock from the keyboard

1. Identify the lock key. Look for a padlock or “Fn Lock” mark, often on Esc but sometimes on another key. The symbol and location vary by model.
2. Check your laptop’s manual. Search the manufacturer’s support page for your exact model and “Fn Lock” or “function key behavior.” Do not assume the same shortcut works across a whole brand.
3. Press the documented shortcut once. If your manual specifies Fn + Esc, hold Fn, tap Esc, then release both. Some HP notebooks use Fn + left Shift; other models may use a different key or may offer no keyboard shortcut.
4. Test the new setting. Press a top-row key by itself and see whether it triggers the F-key command or the printed icon. Then hold Fn and press that key to test the alternate action.
5. Toggle it back if needed. On many models, repeating the same shortcut restores the previous behavior. Check the result instead of relying on a light or on-screen notice, since indicators vary.

Change the default in BIOS or UEFI

If your keyboard has no Fn Lock shortcut, or you want the same behavior every time the computer starts, look for a firmware setting. The exact menu depends on the manufacturer. It may be called Action Keys Mode, Hotkey Mode, Function Key Behavior, or Fn Lock. “Enabled” does not mean the same thing on every model, so read the description beside the option before saving.

1. Save your work. In Windows 10, open Settings > Update & Security > Recovery. Under Advanced startup, choose Restart now.
2. After the restart, select Troubleshoot > Advanced options > UEFI Firmware Settings > Restart. Microsoft notes that Windows 10 reaches Recovery from Update & Security > Recovery; the firmware screen itself is supplied by the PC maker. See Microsoft’s Windows Recovery Environment instructions.
3. In BIOS/UEFI, find the keyboard or function-key setting. HP calls one option Action Keys Mode; Lenovo documents a Hotkey Mode option on supported systems. Dell systems may offer Function Key Behavior or Fn Lock controls. Follow the instructions for your model: see Lenovo’s user guide or Dell’s keyboard guide.
4. Change only the function-key option, save and exit using the firmware’s on-screen command, then test the top row in Windows.

If UEFI Firmware Settings does not appear in Advanced options, use the startup method in your manufacturer’s documentation. The firmware menus are not standardized; avoid changing unrelated boot or security settings.

If the shortcut does not work

• Confirm the exact computer model and look up its manual. A lock symbol may be on a different key, or the model may use a BIOS setting instead of a shortcut.
• Try the one-time method: hold Fn while pressing the desired F key or icon key. This works even when you do not change the default mode, provided that the keyboard supports that action.
• If you use an external keyboard, check that keyboard’s manual separately. Its Fn behavior can be independent of the laptop’s built-in keyboard.
• A Windows key-remapping app cannot reliably add a true Fn Lock when the keyboard firmware does not expose one to Windows. If neither the documented shortcut nor the firmware option exists, the keyboard may not support a persistent toggle.

In short, Windows 10 can take you to your PC’s firmware settings, but the Fn key toggle is controlled by your keyboard or its manufacturer-specific firmware. Use the model’s documented shortcut first, then adjust the firmware option if the shortcut is unavailable.