What Is Debounce?
Debounce (Debounce time, Switch debounce): The short delay a keyboard or mouse uses to ignore switch contact bounce, so one press registers exactly once.
Definition
When the metal contacts in a switch close, they physically bounce for a fraction of a millisecond, making and breaking the connection several times. Debounce is the logic in a keyboard or mouse that waits a short time — typically a few milliseconds — before accepting another press, so one press counts once.
When Debounce Isn’t Enough: Chatter
As switches wear or get dirty, they bounce for longer. If the bounce lasts longer than the debounce time, the extra contact gets through as a second press:
- In a keyboard, a letter types twice — called chatter.
- In a mouse, a single click becomes a double-click.
Adjusting Debounce
Many gaming mice and keyboards (including those running QMK or VIA firmware) let you raise the debounce time. A longer debounce hides mild chatter, at the cost of slightly limiting how fast the same key or button can be repeated. Optical and magnetic switches don’t bounce the same way, so they need little or no debounce.
The chatter and double-click tests time each press to catch bounce that slips through.
Measure It
Related Guides
- How to Fix a Mouse That Double-ClicksFiles opening when you meant to select them, drags that drop halfway — here's how to confirm the fault and fix it, from the quickest checks to a permanent repair.
- Mechanical vs Membrane KeyboardsBoth kinds of keyboard type letters, but they feel, sound, last and fail very differently. Here's how to pick.
Related Terms
Part of the TapTest glossary · More in keyboard tests.