How the double click test works
Click the pad slowly, about once a second, using the button you suspect. The test measures the time between each press and the one before. A deliberate double click takes well over a tenth of a second. When two presses arrive less than 80 ms apart, no finger made the second one: the switch sent it on its own. The test marks it in red and counts it.
After 20 clicks you get a verdict. A fault that comes and goes may need a minute or two of clicking to show itself. Every button is checked separately, so you can test the right and side buttons in the same way.
The limit can be changed. 50 ms is strict and only catches the fastest bounce. 120 ms catches a slower bounce, but at that setting clicking quickly on purpose can trigger it, so keep to one click a second.
Why a mouse double clicks on a single click
Under each button is a small mechanical switch. When its metal contacts meet they do not close cleanly: they bounce for a few thousandths of a second, making and breaking the connection several times. The mouse is built to ignore this. After it sees a press, it disregards further signals for a short period called the debounce time.
As the contacts wear or tarnish, the bouncing lasts longer. Once it outlasts the debounce time, the mouse reads the tail end of one press as a second press. That is why the fault appears on a mouse that used to be fine, starts as an occasional nuisance and gets steadily worse.
Less common causes are a debounce time that has been set too low in the mouse’s software, dirt under the button, and a weak battery or crowded wireless link making a wireless mouse behave erratically.
Rule out the settings first
Two settings can look like this fault without any hardware problem.
- Double-click speed. If it is set very slow, two separate clicks a moment apart are treated as a double click. In Windows: Settings, Bluetooth & devices, Mouse, Additional mouse settings, then the Buttons tab, where the Double-click speed slider is. On a Mac: System Settings, Accessibility, Pointer Control, then Double-click speed.
- Single-click to open. Windows File Explorer can be set to open items with one click, which looks exactly like a double click. It is under File Explorer’s Options, on the General tab, in “Click items as follows”.
Neither setting can turn one press into two. This test looks at raw presses and ignores both settings, so if it reports double clicks, the cause is the mouse.
Fixes to try, in order
- Swap to find the culprit. Run this test with a different mouse on the same computer, and with this mouse on another computer.
- For a wireless mouse, fit a fresh battery or charge it, and bring the receiver closer.
- Raise the debounce time. Some gaming mice expose it in their software. A longer debounce time hides the bounce at the cost of a slightly slower click.
- Update the mouse’s firmware. Some manufacturers have shipped updates that lengthen the debounce time for exactly this problem.
- Clean around the button with compressed air, aiming into the gap at its edge.
- Discharge it. Unplug the mouse, or switch it off and take out the battery, then click the buttons repeatedly for half a minute before reconnecting. Many people report that this helps for a while. It does not repair a worn switch.
- Claim on the warranty. A switch that double clicks is normally covered. Check your warranty before you open the mouse, because opening it usually voids it.
- Replace the switch. This is the permanent fix. It normally means soldering, although a few recent mice have switches that pull out and plug in.
Can software fix it?
There are utilities that discard a second click arriving within a set time of the first. They hide the symptom well enough to keep working, but the switch carries on wearing, and the filter adds a small delay to every click. Treat them as a stopgap until the mouse is repaired or replaced.
To check the rest of the mouse, use the mouse test.