How to Disable Mouse Acceleration

The default settings for the mouse have acceleration enabled. To disable acceleration in the Mouse Control Panel tool, you can move the Mouse Speed slide bar all the way to the left. However, this makes the mouse pointer move very slowly in relation to the movement of the mouse. Disabling acceleration is desirable for some users of Windows NT, such as CAD users, but making the default mouse speed the only speed is impractical.

To calculate the mouse speed under Windows NT, three settings are used: Mouse Speed, MouseThreshold1, and MouseThreshold2.

Mouse Speed sets the relationship between mouse and cursor movement when the value of either MouseThreshold1 or MouseThreshold2 is exceeded. When this occurs, cursor movement accelerates according to the value of MouseSpeed.

MouseThreshold1 and MouseThreshold2 set the maximum number of pixels the mouse can move between mouse interrupts before the system alters the relationship between mouse and cursor movement. If the mouse movement exceeds the threshold defined by MouseThreshold1 and if MouseSpeed is greater than 0, the system moves the cursor at twice the normal speed. If the mouse movement exceeds the threshold defined by MouseThreshold2 and if MouseSpeed is 2, the system moves the cursor at four times the normal speed.

Using the slide bar in the Mouse Control Panel tool, you cannot disable acceleration without making the mouse pointer respond very slowly to the mouse movements. It is possible to overcome this limitation by manually setting the MouseThreshold settings so low that any movement at all is accelerated. Mouse pointer speed will no longer increase factorially with an increase in mouse movement, but still moves at a rate higher than normal.

To implement a higher default mouse pointer speed for the currently logged in user, use the Registry Editor (Regedt32.exe) to edit the following registry key:

HKEY_CURRENT_USER\Control Panel\Mouse

1. Set the value of MouseThreshold1 to 0.
2. Set the value of MouseThreshold2 to 0.
3. Set the value of MouseSpeed to 1 or 2 (1 doubles the normal speed, 2 quadruples the normal speed).
4. Close Registry Editor, close all applications, and restart Windows NT.