Testing for double-click failure
This is the fault that kills most mice, and it is worth understanding because it is repairable.
Inside every mouse button is a small mechanical switch with a metal contact. Over hundreds of thousands of presses that contact oxidises and loses tension, so instead of one clean connection it bounces. The mouse reports two clicks from one press.
To test for it, click the left button slowly and deliberately, once every second or so, twenty times. Watch the double-click counter. It should stay at zero. If it rises without you double-clicking, the switch is failing.
Double-click failure is often fixable. Many mice use a standard Omron switch that costs very little and can be replaced with basic soldering. Some switches can even be revived by opening the housing and gently bending the contact leaf back into tension. Worth trying before discarding an expensive mouse.
What to check
- Left and right should register every deliberate press exactly once.
- Middle is the scroll wheel pressed down. It fails more often than the main buttons because it takes more force.
- Back and forward are the side buttons, if your mouse has them.
- Scroll should count smoothly in both directions. A wheel that jumps back a step while scrolling down has a worn encoder, which is the second most common mouse fault.
- Position updates as you move. Jumpy or frozen coordinates point to a dirty sensor or, on a wireless mouse, interference or a weak battery.
Wireless mice behave differently
Buying second hand? Run the keyboard test and screen test too. If tracking stutters, try a wired connection or move the receiver to a front USB port. USB 3.0 ports and hubs emit interference in the 2.4 GHz band that wireless mice use, and a receiver plugged in next to one is a very common cause of stutter that looks like a failing sensor. A low battery causes the same symptom.
Other checks
Common questions
What is double-click failure?
A worn switch registers one physical press as two clicks. It shows up as files opening when you meant to select them, or drags that break halfway. The double-click counter here rises when two clicks land within 500 milliseconds, so an unintended jump means the switch is failing.
Why are my back and forward buttons not detected?
Some mice map side buttons through their own driver software rather than sending standard button codes. If they work in a browser but not here, they are bound to a macro instead of the standard back and forward actions.
The right button opens a menu instead of registering.
The test area suppresses the context menu so right clicks can be counted. Outside that area, right click behaves normally.
Can this test polling rate or DPI?
Not reliably. Browsers throttle and batch mouse events, so any polling figure measured in a web page is an approximation rather than a real measurement. Use the manufacturer's utility for that.