How can I set the margin of a EditText using xml?

Try this for Right_margin

android:layout_marginRight = "15dip"

Try this for left margin

android:layout_marginLeft = "15dip"

if you give value in center

android:gravity = "center_horizontal"

Try this for left margin the second one in similar:

<EditText 
    android:id="@+id/editText1"
    android:layout_height="wrap_content"
    android:layout_width="wrap_content" 
    android:layout_marginLeft="15dp"
    android:padding="12dp"  
    android:text="EditText" > 
</EditText>