You can put this solution on YOUR website! We do not know unless or until we know the density of the sand. Ounces are units of force or correlated to "mass". One pound is equal to 16 ounces, no matter what the material. You have measurements for a bottle but only with two dimensions, so you also need one more dimension if you want the volume of the bottle.
So you are missing two things: You need one more dimension measurement for the bottle and you need to know the density of the sand.