Dynamically change the width of a button in Android

I assume wrap_content doesn't work for your in your specific case, right? If you need absolute width, then you need to assign that via new LayoutParameters, i.e.

myButton.setLayoutParams(new LinearLayout.LayoutParams(
    30 * someDensityFactor, LinearLayout.LayoutParams.WRAP_CONTENT
))

where the someDensityFactor is your screen density (float). You also might need to invalidate your layout then as well in order to get the button repainted.