fill (something) to (some point)
To insert or place something inside something else, but only to a certain stopping point. Often said of liquids. Well, no wonder she spilled her juice—you filled her cup all the way to the brim! Only fill the box up to here—otherwise, it will be too heavy to carry.
fill something to something
to add material to something up to a certain point. Fill the barrel up to here and no higher. Please fill the glass to the top.